fix: use vars(row) instead of dict(row) in _build_collection_from_bulk

dict() on a types.SimpleNamespace raises TypeError: object is not iterable.
vars() correctly extracts the __dict__ attribute map. Fixes
TestBuildCollectionFailureTracking::test_high_failure_rate_raises_runtime_error.

services/rag_store.py

@@ -290,7 +290,8 @@ def _build_collection_from_bulk(batch_size: int = DEFAULT_BATCH_SIZE) -> dict:
     batch_docs: list[str] = []
     batch_metas: list[dict] = []
     for row in all_rows:
-        card = dict(row)
+        # Support both sqlite3.Row (supports dict()) and SimpleNamespace (needs vars())
+        card = dict(row) if hasattr(row, "keys") else vars(row)
         doc = _build_document(card)
         if not doc.strip():
             continue