feat(#22): implement brain query API

- Create brain module with service, controller, and DTOs
- POST /api/brain/query - Structured queries for tasks, events, projects
- GET /api/brain/context - Get current workspace context for agents
- GET /api/brain/search - Search across all entities
- Support filters: status, priority, date ranges, assignee, etc.
- 41 tests covering service (27) and controller (14)
- Integrated with AuthGuard, WorkspaceGuard, PermissionGuard

apps/api/src/app.module.ts

@@ -16,6 +16,7 @@ import { KnowledgeModule } from "./knowledge/knowledge.module";
 import { UsersModule } from "./users/users.module";
 import { WebSocketModule } from "./websocket/websocket.module";
 import { OllamaModule } from "./ollama/ollama.module";
+import { BrainModule } from "./brain/brain.module";
 
 @Module({
   imports: [
@@ -34,6 +35,7 @@ import { OllamaModule } from "./ollama/ollama.module";
     UsersModule,
     WebSocketModule,
     OllamaModule,
+    BrainModule,
   ],
   controllers: [AppController],
   providers: [AppService],