feat: remove OpenSearch, add ClickHouse admin page

Remove all OpenSearch code, dependencies, configuration, deployment
manifests, and CI/CD references. Replace the OpenSearch admin page
with a ClickHouse admin page showing cluster status, table sizes,
performance metrics, and indexer pipeline stats.

- Delete 11 OpenSearch Java files (config, search impl, admin controller, DTOs, tests)
- Delete 3 OpenSearch frontend files (admin page, CSS, query hooks)
- Delete deploy/opensearch.yaml K8s manifest
- Remove opensearch Maven dependencies from pom.xml
- Remove opensearch config from application.yml, Dockerfile, docker-compose
- Remove opensearch from CI workflow (secrets, deploy, cleanup steps)
- Simplify ThresholdConfig (remove OpenSearch thresholds, database-only)
- Change default search backend from opensearch to clickhouse
- Add ClickHouseAdminController with /status, /tables, /performance, /pipeline
- Add ClickHouseAdminPage with StatCards, pipeline ProgressBar, tables DataTable
- Update CLAUDE.md, HOWTO.md, and source comments

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cameleer3-server-app/src/main/java/com/cameleer3/server/app/dto/ClickHousePerformanceResponse.java

@@ -0,0 +1,12 @@
+package com.cameleer3.server.app.dto;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+@Schema(description = "ClickHouse performance metrics")
+public record ClickHousePerformanceResponse(
+        long queryCount,
+        long insertQueryCount,
+        String memoryUsage,
+        long insertedRows,
+        long readRows
+) {}

cameleer3-server-app/src/main/java/com/cameleer3/server/app/dto/ClickHouseStatusResponse.java

@@ -0,0 +1,11 @@
+package com.cameleer3.server.app.dto;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+@Schema(description = "ClickHouse cluster status")
+public record ClickHouseStatusResponse(
+        boolean reachable,
+        String version,
+        String uptime,
+        String host
+) {}

cameleer3-server-app/src/main/java/com/cameleer3/server/app/dto/ClickHouseTableInfo.java

@@ -0,0 +1,13 @@
+package com.cameleer3.server.app.dto;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+@Schema(description = "ClickHouse table information")
+public record ClickHouseTableInfo(
+        String name,
+        String engine,
+        long rowCount,
+        String dataSize,
+        long dataSizeBytes,
+        int partitionCount
+) {}

cameleer3-server-app/src/main/java/com/cameleer3/server/app/dto/IndexInfoResponse.java

@@ -1,14 +0,0 @@
-package com.cameleer3.server.app.dto;
-
-import io.swagger.v3.oas.annotations.media.Schema;
-
-@Schema(description = "OpenSearch index information")
-public record IndexInfoResponse(
-        @Schema(description = "Index name") String name,
-        @Schema(description = "Document count") long docCount,
-        @Schema(description = "Human-readable index size") String size,
-        @Schema(description = "Index size in bytes") long sizeBytes,
-        @Schema(description = "Index health status") String health,
-        @Schema(description = "Number of primary shards") int primaryShards,
-        @Schema(description = "Number of replica shards") int replicaShards
-) {}

cameleer3-server-app/src/main/java/com/cameleer3/server/app/dto/IndexerPipelineResponse.java

@@ -0,0 +1,16 @@
+package com.cameleer3.server.app.dto;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+import java.time.Instant;
+
+@Schema(description = "Search indexer pipeline statistics")
+public record IndexerPipelineResponse(
+        int queueDepth,
+        int maxQueueSize,
+        long failedCount,
+        long indexedCount,
+        long debounceMs,
+        double indexingRate,
+        Instant lastIndexedAt
+) {}

cameleer3-server-app/src/main/java/com/cameleer3/server/app/dto/IndicesPageResponse.java

@@ -1,16 +0,0 @@
-package com.cameleer3.server.app.dto;
-
-import io.swagger.v3.oas.annotations.media.Schema;
-
-import java.util.List;
-
-@Schema(description = "Paginated list of OpenSearch indices")
-public record IndicesPageResponse(
-        @Schema(description = "Index list for current page") List<IndexInfoResponse> indices,
-        @Schema(description = "Total number of indices") long totalIndices,
-        @Schema(description = "Total document count across all indices") long totalDocs,
-        @Schema(description = "Human-readable total size") String totalSize,
-        @Schema(description = "Current page number (0-based)") int page,
-        @Schema(description = "Page size") int pageSize,
-        @Schema(description = "Total number of pages") int totalPages
-) {}

cameleer3-server-app/src/main/java/com/cameleer3/server/app/dto/LogEntryResponse.java

@@ -2,7 +2,7 @@ package com.cameleer3.server.app.dto;
 
 import io.swagger.v3.oas.annotations.media.Schema;
 
-@Schema(description = "Application log entry from OpenSearch")
+@Schema(description = "Application log entry")
 public record LogEntryResponse(
         @Schema(description = "Log timestamp (ISO-8601)") String timestamp,
         @Schema(description = "Log level (INFO, WARN, ERROR, DEBUG)") String level,

cameleer3-server-app/src/main/java/com/cameleer3/server/app/dto/OpenSearchStatusResponse.java

@@ -1,12 +0,0 @@
-package com.cameleer3.server.app.dto;
-
-import io.swagger.v3.oas.annotations.media.Schema;
-
-@Schema(description = "OpenSearch cluster status")
-public record OpenSearchStatusResponse(
-        @Schema(description = "Whether the cluster is reachable") boolean reachable,
-        @Schema(description = "Cluster health status (GREEN, YELLOW, RED)") String clusterHealth,
-        @Schema(description = "OpenSearch version") String version,
-        @Schema(description = "Number of nodes in the cluster") int nodeCount,
-        @Schema(description = "OpenSearch host") String host
-) {}

cameleer3-server-app/src/main/java/com/cameleer3/server/app/dto/PerformanceResponse.java

@@ -1,13 +0,0 @@
-package com.cameleer3.server.app.dto;
-
-import io.swagger.v3.oas.annotations.media.Schema;
-
-@Schema(description = "OpenSearch performance metrics")
-public record PerformanceResponse(
-        @Schema(description = "Query cache hit rate (0.0-1.0)") double queryCacheHitRate,
-        @Schema(description = "Request cache hit rate (0.0-1.0)") double requestCacheHitRate,
-        @Schema(description = "Average search latency in milliseconds") double searchLatencyMs,
-        @Schema(description = "Average indexing latency in milliseconds") double indexingLatencyMs,
-        @Schema(description = "JVM heap used in bytes") long jvmHeapUsedBytes,
-        @Schema(description = "JVM heap max in bytes") long jvmHeapMaxBytes
-) {}

cameleer3-server-app/src/main/java/com/cameleer3/server/app/dto/PipelineStatsResponse.java

@@ -1,16 +0,0 @@
-package com.cameleer3.server.app.dto;
-
-import io.swagger.v3.oas.annotations.media.Schema;
-
-import java.time.Instant;
-
-@Schema(description = "Search indexing pipeline statistics")
-public record PipelineStatsResponse(
-        @Schema(description = "Current queue depth") int queueDepth,
-        @Schema(description = "Maximum queue size") int maxQueueSize,
-        @Schema(description = "Number of failed indexing operations") long failedCount,
-        @Schema(description = "Number of successfully indexed documents") long indexedCount,
-        @Schema(description = "Debounce interval in milliseconds") long debounceMs,
-        @Schema(description = "Current indexing rate (docs/sec)") double indexingRate,
-        @Schema(description = "Timestamp of last indexed document") Instant lastIndexedAt
-) {}

cameleer3-server-app/src/main/java/com/cameleer3/server/app/dto/ThresholdConfigRequest.java

@@ -5,18 +5,15 @@ import io.swagger.v3.oas.annotations.media.Schema;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.Max;
 import jakarta.validation.constraints.Min;
-import jakarta.validation.constraints.NotBlank;
 import jakarta.validation.constraints.NotNull;
 import jakarta.validation.constraints.Positive;
 
 import java.util.ArrayList;
 import java.util.List;
-import java.util.Map;
 
 @Schema(description = "Threshold configuration for admin monitoring")
 public record ThresholdConfigRequest(
-        @Valid @NotNull DatabaseThresholdsRequest database,
-        @Valid @NotNull OpenSearchThresholdsRequest opensearch
+        @Valid @NotNull DatabaseThresholdsRequest database
 ) {
 
     @Schema(description = "Database monitoring thresholds")
@@ -38,41 +35,6 @@ public record ThresholdConfigRequest(
             double queryDurationCritical
     ) {}
 
-    @Schema(description = "OpenSearch monitoring thresholds")
-    public record OpenSearchThresholdsRequest(
-            @NotBlank
-            @Schema(description = "Cluster health warning threshold (GREEN, YELLOW, RED)")
-            String clusterHealthWarning,
-
-            @NotBlank
-            @Schema(description = "Cluster health critical threshold (GREEN, YELLOW, RED)")
-            String clusterHealthCritical,
-
-            @Min(0)
-            @Schema(description = "Queue depth warning threshold")
-            int queueDepthWarning,
-
-            @Min(0)
-            @Schema(description = "Queue depth critical threshold")
-            int queueDepthCritical,
-
-            @Min(0) @Max(100)
-            @Schema(description = "JVM heap usage warning threshold (percentage)")
-            int jvmHeapWarning,
-
-            @Min(0) @Max(100)
-            @Schema(description = "JVM heap usage critical threshold (percentage)")
-            int jvmHeapCritical,
-
-            @Min(0)
-            @Schema(description = "Failed document count warning threshold")
-            int failedDocsWarning,
-
-            @Min(0)
-            @Schema(description = "Failed document count critical threshold")
-            int failedDocsCritical
-    ) {}
-
     /** Convert to core domain model */
     public ThresholdConfig toConfig() {
         return new ThresholdConfig(
@@ -81,16 +43,6 @@ public record ThresholdConfigRequest(
                         database.connectionPoolCritical(),
                         database.queryDurationWarning(),
                         database.queryDurationCritical()
-                ),
-                new ThresholdConfig.OpenSearchThresholds(
-                        opensearch.clusterHealthWarning(),
-                        opensearch.clusterHealthCritical(),
-                        opensearch.queueDepthWarning(),
-                        opensearch.queueDepthCritical(),
-                        opensearch.jvmHeapWarning(),
-                        opensearch.jvmHeapCritical(),
-                        opensearch.failedDocsWarning(),
-                        opensearch.failedDocsCritical()
                 )
         );
     }
@@ -108,37 +60,6 @@ public record ThresholdConfigRequest(
             }
         }
 
-        if (opensearch != null) {
-            if (opensearch.queueDepthWarning() > opensearch.queueDepthCritical()) {
-                errors.add("opensearch.queueDepthWarning must be <= queueDepthCritical");
-            }
-            if (opensearch.jvmHeapWarning() > opensearch.jvmHeapCritical()) {
-                errors.add("opensearch.jvmHeapWarning must be <= jvmHeapCritical");
-            }
-            if (opensearch.failedDocsWarning() > opensearch.failedDocsCritical()) {
-                errors.add("opensearch.failedDocsWarning must be <= failedDocsCritical");
-            }
-            // Validate health severity ordering: GREEN < YELLOW < RED
-            int warningSeverity = healthSeverity(opensearch.clusterHealthWarning());
-            int criticalSeverity = healthSeverity(opensearch.clusterHealthCritical());
-            if (warningSeverity < 0) {
-                errors.add("opensearch.clusterHealthWarning must be GREEN, YELLOW, or RED");
-            }
-            if (criticalSeverity < 0) {
-                errors.add("opensearch.clusterHealthCritical must be GREEN, YELLOW, or RED");
-            }
-            if (warningSeverity >= 0 && criticalSeverity >= 0 && warningSeverity > criticalSeverity) {
-                errors.add("opensearch.clusterHealthWarning severity must be <= clusterHealthCritical (GREEN < YELLOW < RED)");
-            }
-        }
-
         return errors;
     }
-
-    private static final Map<String, Integer> HEALTH_SEVERITY =
-            Map.of("GREEN", 0, "YELLOW", 1, "RED", 2);
-
-    private static int healthSeverity(String health) {
-        return HEALTH_SEVERITY.getOrDefault(health != null ? health.toUpperCase() : "", -1);
-    }
 }