feat(#380): Workspace-to-Matrix-Room mapping and provisioning

- Add matrix_room_id column to workspace table (migration)
- Create MatrixRoomService for room provisioning and mapping
- Auto-create Matrix room on workspace provisioning (when configured)
- Support manual room linking for existing workspaces
- Unit tests for all mapping operations

Refs #380

apps/api/src/bridge/matrix/index.ts

@@ -1 +1,2 @@
 export { MatrixService } from "./matrix.service";
+export { MatrixRoomService } from "./matrix-room.service";