refactor: rename group/groupName to application/applicationName

The execution-related "group" concept actually represents the
application name. Rename all Java fields, API parameters, and frontend
types from groupName→applicationName and group→application for clarity.

- Java records: ExecutionSummary, ExecutionDetail, ExecutionDocument,
  ExecutionRecord, ProcessorRecord
- API params: SearchRequest.group→application, SearchController
  @RequestParam group→application
- Services: IngestionService, DetailService, SearchIndexer, StatsStore
- Frontend: schema.d.ts, Dashboard, ExchangeDetail, RouteDetail,
  executions query hooks

Database column names (group_name) and OpenSearch field names are
unchanged — only the API-facing Java/TS field names are renamed.

RBAC group references (groups table, GroupRepository, GroupsTab) are
a separate domain concept and are NOT affected by this change.

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

ui/src/pages/Dashboard/Dashboard.tsx

@@ -36,7 +36,7 @@ export default function Dashboard() {
   const { data: searchResult } = useSearchExecutions({
     timeFrom, timeTo,
     routeId: routeId || undefined,
-    group: appId || undefined,
+    application: appId || undefined,
     offset: 0, limit: 50,
   }, true);
   const { data: detail } = useExecutionDetail(selectedId);
@@ -94,7 +94,7 @@ export default function Dashboard() {
       ),
     },
     { key: 'routeId', header: 'Route', sortable: true, render: (v) => <span>{String(v)}</span> },
-    { key: 'groupName', header: 'Application', sortable: true, render: (v) => <span>{String(v ?? '')}</span> },
+    { key: 'applicationName', header: 'Application', sortable: true, render: (v) => <span>{String(v ?? '')}</span> },
     { key: 'executionId', header: 'Exchange ID', sortable: true, render: (v) => <MonoText size="xs">{String(v)}</MonoText> },
     { key: 'startTime', header: 'Started', sortable: true, render: (v) => <MonoText size="xs">{new Date(v as string).toISOString().replace('T', ' ').slice(0, 19)}</MonoText> },
     {