refactor(search): drop dead SearchIndexer subsystem

After the ExecutionController removal (0f635576), SearchIndexer
subscribed to ExecutionUpdatedEvent but nothing publishes that event.
Every SearchIndexerStats metric returned always-zero, and the admin
/api/v1/admin/clickhouse/pipeline endpoint that surfaced those stats
carried no signal.

Backend removed:
- core: SearchIndexer, SearchIndexerStats, ExecutionUpdatedEvent
- app: IndexerPipelineResponse DTO, /pipeline endpoint on
  ClickHouseAdminController (field + ctor param)
- StorageBeanConfig.searchIndexer bean

UI removed:
- IndexerPipeline type + useIndexerPipeline hook in
  api/queries/admin/clickhouse.ts
- Indexer Pipeline card in ClickHouseAdminPage.tsx (plus ProgressBar
  import and pipeline* CSS classes)

OpenAPI schema.d.ts + openapi.json regenerated (stale /pipeline path
and IndexerPipelineResponse schema removed).

SearchIndex interface + ClickHouseSearchIndex impl kept — those are
live and used by SearchService + ExchangeMatchEvaluator.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

ui/src/pages/Admin/ClickHouseAdminPage.module.css

@@ -5,30 +5,6 @@
   flex-wrap: wrap;
 }
 
-/* pipelineCard — card styling via sectionStyles.section */
-.pipelineCard {
-  margin-bottom: 16px;
-}
-
-.pipelineTitle {
-  font-size: 13px;
-  font-weight: 600;
-  color: var(--text-primary);
-  margin-bottom: 8px;
-}
-
-.pipelineMetrics {
-  display: flex;
-  gap: 24px;
-  margin-top: 8px;
-  font-size: 12px;
-  color: var(--text-muted);
-}
-
-.pipelineMetrics span {
-  font-family: var(--font-mono);
-}
-
 .tableSection {
   margin-bottom: 16px;
 }

ui/src/pages/Admin/ClickHouseAdminPage.tsx

@@ -1,8 +1,7 @@
-import { StatCard, DataTable, ProgressBar } from '@cameleer/design-system';
+import { StatCard, DataTable } from '@cameleer/design-system';
 import type { Column } from '@cameleer/design-system';
-import { useClickHouseStatus, useClickHouseTables, useClickHousePerformance, useClickHouseQueries, useIndexerPipeline } from '../../api/queries/admin/clickhouse';
+import { useClickHouseStatus, useClickHouseTables, useClickHousePerformance, useClickHouseQueries } from '../../api/queries/admin/clickhouse';
 import styles from './ClickHouseAdminPage.module.css';
-import sectionStyles from '../../styles/section-card.module.css';
 import tableStyles from '../../styles/table-section.module.css';
 
 export default function ClickHouseAdminPage() {
@@ -10,7 +9,6 @@ export default function ClickHouseAdminPage() {
   const { data: tables } = useClickHouseTables();
   const { data: perf } = useClickHousePerformance();
   const { data: queries } = useClickHouseQueries();
-  const { data: pipeline } = useIndexerPipeline();
   const unreachable = statusError || (status && !status.reachable);
 
   const totalSize = (tables || []).reduce((sum, t) => sum + (t.dataSizeBytes || 0), 0);
@@ -52,20 +50,6 @@ export default function ClickHouseAdminPage() {
         </div>
       )}
 
-      {/* Pipeline */}
-      {pipeline && (
-        <div className={`${sectionStyles.section} ${styles.pipelineCard}`}>
-          <div className={styles.pipelineTitle}>Indexer Pipeline</div>
-          <ProgressBar value={pipeline.maxQueueSize > 0 ? (pipeline.queueDepth / pipeline.maxQueueSize) * 100 : 0} />
-          <div className={styles.pipelineMetrics}>
-            <span>Queue: {pipeline.queueDepth}/{pipeline.maxQueueSize}</span>
-            <span>Indexed: {pipeline.indexedCount.toLocaleString()}</span>
-            <span>Failed: {pipeline.failedCount}</span>
-            <span>Rate: {pipeline.indexingRate.toFixed(1)}/s</span>
-          </div>
-        </div>
-      )}
-
       {/* Tables */}
       <div className={`${tableStyles.tableSection} ${styles.tableSection}`}>
         <div className={tableStyles.tableHeader}>