fix: improve ClickHouse admin page, fix AgentHealth type error

Rewrite ClickHouse admin to show useful storage metrics instead of
often-empty system.events data. Add active queries section.

- Replace performance endpoint: query system.parts for disk size,
  uncompressed size, compression ratio, total rows, part count
- Add /queries endpoint querying system.processes for active queries
- Frontend: storage overview strip, tables with total size, active
  queries DataTable
- Fix AgentHealth.tsx type: agentId → instanceId in inline type cast

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

@@ -2,11 +2,13 @@ package com.cameleer3.server.app.dto;
 
 import io.swagger.v3.oas.annotations.media.Schema;
 
-@Schema(description = "ClickHouse performance metrics")
+@Schema(description = "ClickHouse storage and performance metrics")
 public record ClickHousePerformanceResponse(
-        long queryCount,
-        long insertQueryCount,
+        String diskSize,
+        String uncompressedSize,
+        double compressionRatio,
+        long totalRows,
+        int partCount,
         String memoryUsage,
-        long insertedRows,
-        long readRows
+        int currentQueries
 ) {}

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

@@ -0,0 +1,12 @@
+package com.cameleer3.server.app.dto;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+@Schema(description = "Active ClickHouse query information")
+public record ClickHouseQueryInfo(
+        String queryId,
+        double elapsedSeconds,
+        String memory,
+        long readRows,
+        String query
+) {}