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.

app/plugins/builtins/unified_search/schemas.py

@@ -14,6 +14,19 @@ class SearchRequest(BaseModel):
     entity_types: list[str] | None = None
     limit: int = Field(default=20, ge=1, le=100)
     offset: int = Field(default=0, ge=0)
+    date_from: str | None = Field(
+        default=None, description="ISO date (YYYY-MM-DD) — filter by created_at/updated_at >= date_from"
+    )
+    date_to: str | None = Field(
+        default=None, description="ISO date (YYYY-MM-DD) — filter by created_at/updated_at <= date_to"
+    )
+    tags: list[str] | None = Field(
+        default=None, description="Filter results by tags (comma-separated on entities)"
+    )
+    sort: str = Field(
+        default="relevance",
+        description="Sort order: relevance, date, name",
+    )
 
 
 class SearchResult(BaseModel):
@@ -34,6 +47,14 @@ class SearchResponse(BaseModel):
     suggestions: list[str]
 
 
+class FacetsResponse(BaseModel):
+    """Available facets for search filtering."""
+
+    entity_types: list[str]
+    tags: list[str]
+    date_ranges: dict[str, Any]
+
+
 # ─── Similar ───
 
 class SimilarRequest(BaseModel):
@@ -61,6 +82,7 @@ class SuggestResponse(BaseModel):
 
 class ReindexRequest(BaseModel):
     entity_types: list[str] = Field(default_factory=list)
+    include_chunks: bool = Field(default=True, description="Re-index document chunks for files")
 
 
 # ─── Provider ───
@@ -69,3 +91,7 @@ class ProviderResponse(BaseModel):
     entity_type: str
     plugin_name: str
     is_active: bool
+    supports_fts: bool = True
+    supports_vector: bool = True
+    supports_rag: bool = False
+    supports_graph: bool = False