enh: kb metadata search

backend/open_webui/retrieval/vector/dbs/chroma.py

@@ -69,7 +69,7 @@ class ChromaClient(VectorDBBase):
         return self.client.delete_collection(name=collection_name)
 
     def search(
-        self, collection_name: str, vectors: list[list[float | int]], limit: int
+        self, collection_name: str, vectors: list[list[float | int]], filter: Optional[dict] = None, limit: int = 10
     ) -> Optional[SearchResult]:
         # Search for the nearest neighbor items based on the vectors and return 'limit' number of results.
         try:
@@ -78,6 +78,7 @@ class ChromaClient(VectorDBBase):
                 result = collection.query(
                     query_embeddings=vectors,
                     n_results=limit,
+                    where=filter,
                 )
 
                 # chromadb has cosine distance, 2 (worst) -> 0 (best). Re-odering to 0 -> 1