feat(admin): add Query Inspector for RAG pipeline inspection

Summary

Integrate the Query Inspector admin feature that enables administrators to inspect the full RAG pipeline for each processed query: user question, context sent to RAG, retrieved documents with relevance scores, LLM response with confidence score, and user feedback.

Backend

• getQueriesForInspector() — paginated AQL query with filters (searchText, confidence range, date range, userId)
• getQueryInspectorDetails() — full query document with user name resolution
• 2 new routes: GET /admin/queries/inspect and GET /admin/queries/inspect/:queryId
• Input validation: date parsing, numeric range checks, parameter whitelist
• Full Swagger/OpenAPI documentation

Frontend

• 3 Vue components (Options API, DS design system, scoped CSS with design tokens)
  • QueryInspector — root with list/detail view toggle
  • QueryInspectorList — table with filters and pagination
  • QueryInspectorDetail — full inspection view with all RAG pipeline sections
• i18n via translate() pattern
• AdminDashboard integration (sidebar nav + tab)

Tests — 62 total, all passing

• Backend: 20 service tests + 11 route tests
• Frontend: 5 service tests + 26 component tests
• Coverage >80% on all new code (statements, branches, lines)

Code Review fixes applied

• Date input validation (prevents invalid date strings in AQL)
• Numeric confidence range validation (prevents NaN in queries)
• Parameter whitelist in route handler (prevents parameter pollution)
• Swagger security scheme harmonized with existing routes (KeycloakOAuth2)

Test plan

• Run backend tests: npx jest __tests__/services/query-service-inspector.test.js __tests__/routes/admin-inspector.test.js
• Run frontend tests: npx jest src/__tests__/adminDashboardService-inspector.test.js src/__tests__/components/QueryInspector.test.js
• Start backend, authenticate as admin, verify GET /api/admin/queries/inspect?limit=5 returns data
• Open admin dashboard in browser, navigate to Query Inspector tab
• Verify list loads with pagination, filters work, row click opens detail view
• Verify detail shows all sections: question, context, messages, documents, response, feedback