feat: add Logs tab with cursor-paginated search, level filters, and live tail

- Extend GET /api/v1/logs with cursor pagination, multi-level filtering,
  optional application scoping, and level count aggregation
- Add exchangeId, instanceId, application, mdc fields to log responses
- Refactor ClickHouseLogStore with keyset pagination (N+1 pattern)
- Add LogSearchRequest/LogSearchResponse core domain records
- Create LogSearchPageResponse wrapper DTO
- Add Logs as 4th content tab (Exchanges | Dashboard | Runtime | Logs)
- Implement LogSearch component with debounced search, level filter bar,
  expandable log entries, cursor pagination, and live tail mode
- Add cross-navigation: exchange header → logs, log tab → logs tab
- Update ClickHouseLogStoreIT with cursor, multi-level, cross-app tests

Closes: #104

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

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

@@ -2,12 +2,18 @@ package com.cameleer3.server.app.dto;
 
 import io.swagger.v3.oas.annotations.media.Schema;
 
+import java.util.Map;
+
 @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,
+        @Schema(description = "Log level (INFO, WARN, ERROR, DEBUG, TRACE)") String level,
         @Schema(description = "Logger name") String loggerName,
         @Schema(description = "Log message") String message,
         @Schema(description = "Thread name") String threadName,
-        @Schema(description = "Stack trace (if present)") String stackTrace
+        @Schema(description = "Stack trace (if present)") String stackTrace,
+        @Schema(description = "Camel exchange ID (if present)") String exchangeId,
+        @Schema(description = "Agent instance ID") String instanceId,
+        @Schema(description = "Application ID") String application,
+        @Schema(description = "MDC context map") Map<String, String> mdc
 ) {}

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

@@ -0,0 +1,14 @@
+package com.cameleer3.server.app.dto;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+import java.util.List;
+import java.util.Map;
+
+@Schema(description = "Log search response with cursor pagination and level counts")
+public record LogSearchPageResponse(
+        @Schema(description = "Log entries for the current page") List<LogEntryResponse> data,
+        @Schema(description = "Cursor for next page (null if no more results)") String nextCursor,
+        @Schema(description = "Whether more results exist beyond this page") boolean hasMore,
+        @Schema(description = "Count of logs per level (unaffected by level filter)") Map<String, Long> levelCounts
+) {}