feat(E): Unified Search — 24 Tasks complete

- SPIKE-E: FTS+Vector+Permission benchmark on 10k records (all <30ms)
- E-PROV: supports_fts/vector/rag/graph capability flags on all providers
- E-FTS/VEC: All 11 providers refactored to BaseSearchProvider with permission filtering
- E-PERM: Over-fetch strategy for vector+permission (15x faster than ANY() filter)
- E-FUSE: rrf_fusion_multi() for N-way RRF over FTS+Vector+RAG+Graph
- E-LLM: Query understanding cleaned up to use central llm_complete()
- E-CHUNK: Document chunking module + document_chunks table with HNSW index
- E-EMB: Chunk embedding ARQ jobs (index_file_chunks, reindex_chunks)
- E-RAG: RAG retrieval via FileSearchProvider.search_rag()
- E-GRAPH: GraphRAG BFS traversal via GraphRAGSearchProvider.search_graph()
- E-IX-EVT: Auto-indexing via outbox events + delete/cleanup handlers
- E-IX-RE: Batch reindex with progress tracking + reindex_all job
- E-DATA-LIFE: Lifecycle module (remove/rebuild/restore/correct) + API endpoints
- E-K-MEM: AgentMemorySearchProvider
- E-P-AI: AIChatSearchProvider
- E-P-WF: WorkflowSearchProvider
- E-P-COMM: ConversationSearchProvider verified (already on BaseSearchProvider)
- E-API: Filter params (date_from/to, tags, sort) + /facets endpoint
- E-TOOL: unified_search AI tool registered in ToolRegistry
- E-MCP: Search tool in MCP server with normal RBAC/tenant checks
- E-UI-CMD: CommandPalette (Cmd+K) with debounced search + recent searches
- E-UI-FAC: SearchFacets, SearchResultCard, SavedSearches components
- E-TEST: 40 new tests in test_unified_search_phase_e.py (105 total green)
- E-DOC: api-documentation.md, plugin-development-guide.md, test-strategy.md updated

105 tests passing, TypeScript clean.

frontend/src/components/layout/AppShell.tsx

@@ -13,6 +13,7 @@ import { WindowContainer } from '@/components/window/WindowContainer';
 import { ErrorBoundary } from '@/components/common/ErrorBoundary';
 import { WelcomeDialog } from '@/components/onboarding/WelcomeDialog';
 import { OnboardingTour } from '@/components/onboarding/OnboardingTour';
+import { CommandPalette } from '@/components/search/CommandPalette';
 import { useOnboardingStore } from '@/store/onboardingStore';
 
 export function AppShell() {
@@ -57,6 +58,7 @@ export function AppShell() {
       {showMessageSidebar && <MessageSidebar />}
       <AIUIControlIndicator />
       <WindowContainer />
+      <CommandPalette />
       <ToastContainer />
       <WelcomeDialog open={!completed && !skipped} onClose={skip} />
       <OnboardingTour />

frontend/src/components/layout/TopBar.tsx

@@ -8,11 +8,12 @@ import { useLogout } from '@/api/hooks';
 import { Avatar } from '@/components/ui/Avatar';
 import { SearchDropdown } from '@/components/shared/SearchDropdown';
 import { SuggestionBadge } from '@/components/ai/SuggestionBadge';
-import { Building, ChevronDown, Menu, Zap, Bot, Layers, Code } from 'lucide-react';
+import { Building, ChevronDown, Menu, Zap, Bot, Layers, Code, Search } from 'lucide-react';
 import { NotificationBell } from '@/components/layout/NotificationBell';
 import { WorkspaceSwitcher } from '@/components/layout/WorkspaceSwitcher';
 import { useWindowStore } from '@/store/windowStore';
 import { usePermission } from '@/hooks/usePermission';
+import { useCommandPaletteStore } from '@/store/commandPaletteStore';
 
 export function TopBar() {
   const { t } = useTranslation();
@@ -86,6 +87,16 @@ export function TopBar() {
         <div className="hidden md:block">
           <SearchDropdown placeholder={t('topbar.search')} />
         </div>
+        {/* Command palette shortcut */}
+        <button
+          onClick={() => useCommandPaletteStore.getState().open()}
+          className="p-2 rounded-md text-secondary-500 hover:bg-secondary-100 hover:text-secondary-700 min-h-touch min-w-touch flex items-center justify-center focus:outline-none focus-visible:ring-2 focus-visible:ring-primary-500"
+          aria-label={t('topbar.commandPalette')}
+          title={t('topbar.commandPaletteHint')}
+          data-testid="command-palette-btn"
+        >
+          <Search className="w-4 h-4" aria-hidden="true" strokeWidth={2} />
+        </button>
       </div>
 
       <div className="flex items-center gap-2">