Ignore local ChromaDB artifacts

.gitignore

@@ -41,6 +41,7 @@ dev-tools/query-expansion-tests/
 .env.local
 .env
 
-# We exclude data/chroma_db/ to include pre-built embeddings for deployment
-# data/chroma_db/
-# Note: data/chroma_db/ is now tracked to include pre-built embeddings for deployment --- IGNORE ---
+# Ignore local ChromaDB persistence (binary DB files). These should not be
+# committed; remove them from history before pushing to remote Spaces.
+data/chroma_db/
+data/chroma_db/*