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>

ui/src/api/queries/admin/clickhouse.ts

@@ -0,0 +1,77 @@
+import { useQuery } from '@tanstack/react-query';
+import { adminFetch } from './admin-api';
+import { useRefreshInterval } from '../use-refresh-interval';
+
+// ── Types ──────────────────────────────────────────────────────────────
+
+export interface ClickHouseStatus {
+  reachable: boolean;
+  version: string | null;
+  uptime: string | null;
+  host: string | null;
+}
+
+export interface ClickHouseTableInfo {
+  name: string;
+  engine: string;
+  rowCount: number;
+  dataSize: string;
+  dataSizeBytes: number;
+  partitionCount: number;
+}
+
+export interface ClickHousePerformance {
+  queryCount: number;
+  insertQueryCount: number;
+  memoryUsage: string;
+  insertedRows: number;
+  readRows: number;
+}
+
+export interface IndexerPipeline {
+  queueDepth: number;
+  maxQueueSize: number;
+  failedCount: number;
+  indexedCount: number;
+  debounceMs: number;
+  indexingRate: number;
+  lastIndexedAt: string | null;
+}
+
+// ── Query Hooks ────────────────────────────────────────────────────────
+
+export function useClickHouseStatus() {
+  const refetchInterval = useRefreshInterval(30_000);
+  return useQuery({
+    queryKey: ['admin', 'clickhouse', 'status'],
+    queryFn: () => adminFetch<ClickHouseStatus>('/clickhouse/status'),
+    refetchInterval,
+  });
+}
+
+export function useClickHouseTables() {
+  const refetchInterval = useRefreshInterval(60_000);
+  return useQuery({
+    queryKey: ['admin', 'clickhouse', 'tables'],
+    queryFn: () => adminFetch<ClickHouseTableInfo[]>('/clickhouse/tables'),
+    refetchInterval,
+  });
+}
+
+export function useClickHousePerformance() {
+  const refetchInterval = useRefreshInterval(30_000);
+  return useQuery({
+    queryKey: ['admin', 'clickhouse', 'performance'],
+    queryFn: () => adminFetch<ClickHousePerformance>('/clickhouse/performance'),
+    refetchInterval,
+  });
+}
+
+export function useIndexerPipeline() {
+  const refetchInterval = useRefreshInterval(10_000);
+  return useQuery({
+    queryKey: ['admin', 'clickhouse', 'pipeline'],
+    queryFn: () => adminFetch<IndexerPipeline>('/clickhouse/pipeline'),
+    refetchInterval,
+  });
+}

ui/src/api/queries/admin/opensearch.ts

@@ -1,109 +0,0 @@
-import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
-import { adminFetch } from './admin-api';
-import { useRefreshInterval } from '../use-refresh-interval';
-
-// ── Types ──────────────────────────────────────────────────────────────
-
-export interface OpenSearchStatus {
-  reachable: boolean;
-  clusterHealth: string;
-  version: string | null;
-  nodeCount: number;
-  host: string;
-}
-
-export interface PipelineStats {
-  queueDepth: number;
-  maxQueueSize: number;
-  failedCount: number;
-  indexedCount: number;
-  debounceMs: number;
-  indexingRate: number;
-  lastIndexedAt: string | null;
-}
-
-export interface IndexInfo {
-  name: string;
-  docCount: number;
-  size: string;
-  sizeBytes: number;
-  health: string;
-  primaryShards: number;
-  replicas: number;
-}
-
-export interface IndicesPage {
-  indices: IndexInfo[];
-  totalIndices: number;
-  totalDocs: number;
-  totalSize: string;
-  page: number;
-  pageSize: number;
-  totalPages: number;
-}
-
-export interface PerformanceStats {
-  queryCacheHitRate: number;
-  requestCacheHitRate: number;
-  searchLatencyMs: number;
-  indexingLatencyMs: number;
-  heapUsedBytes: number;
-  heapMaxBytes: number;
-}
-
-// ── Query Hooks ────────────────────────────────────────────────────────
-
-export function useOpenSearchStatus() {
-  const refetchInterval = useRefreshInterval(30_000);
-  return useQuery({
-    queryKey: ['admin', 'opensearch', 'status'],
-    queryFn: () => adminFetch<OpenSearchStatus>('/opensearch/status'),
-    refetchInterval,
-  });
-}
-
-export function usePipelineStats() {
-  const refetchInterval = useRefreshInterval(10_000);
-  return useQuery({
-    queryKey: ['admin', 'opensearch', 'pipeline'],
-    queryFn: () => adminFetch<PipelineStats>('/opensearch/pipeline'),
-    refetchInterval,
-  });
-}
-
-export function useOpenSearchIndices(page = 0, size = 20, search = '', prefix = 'executions') {
-  return useQuery({
-    queryKey: ['admin', 'opensearch', 'indices', prefix, page, size, search],
-    queryFn: () => {
-      const params = new URLSearchParams();
-      params.set('page', String(page));
-      params.set('size', String(size));
-      params.set('prefix', prefix);
-      if (search) params.set('search', search);
-      return adminFetch<IndicesPage>(`/opensearch/indices?${params}`);
-    },
-    placeholderData: (prev) => prev,
-  });
-}
-
-export function useOpenSearchPerformance() {
-  const refetchInterval = useRefreshInterval(30_000);
-  return useQuery({
-    queryKey: ['admin', 'opensearch', 'performance'],
-    queryFn: () => adminFetch<PerformanceStats>('/opensearch/performance'),
-    refetchInterval,
-  });
-}
-
-// ── Mutation Hooks ─────────────────────────────────────────────────────
-
-export function useDeleteIndex() {
-  const qc = useQueryClient();
-  return useMutation({
-    mutationFn: (indexName: string) =>
-      adminFetch<void>(`/opensearch/indices/${indexName}`, { method: 'DELETE' }),
-    onSuccess: () => {
-      qc.invalidateQueries({ queryKey: ['admin', 'opensearch', 'indices'] });
-    },
-  });
-}

ui/src/api/queries/admin/thresholds.ts

@@ -10,20 +10,8 @@ export interface DatabaseThresholds {
   queryDurationCritical: number;
 }
 
-export interface OpenSearchThresholds {
-  clusterHealthWarning: string;
-  clusterHealthCritical: string;
-  queueDepthWarning: number;
-  queueDepthCritical: number;
-  jvmHeapWarning: number;
-  jvmHeapCritical: number;
-  failedDocsWarning: number;
-  failedDocsCritical: number;
-}
-
 export interface ThresholdConfig {
   database: DatabaseThresholds;
-  opensearch: OpenSearchThresholds;
 }
 
 // ── Query Hooks ────────────────────────────────────────────────────────