Update vector query methods to support ID filtering in PostgreSQL

- Modified `mix_kg_vector_query` in operate.py to pass optional IDs to vector search
- Updated PostgreSQL SQL template to filter results using document IDs instead of chunk_id
- Improved query flexibility by allowing precise document selection during vector search

lightrag/kg/postgres_impl.py

@@ -1597,7 +1597,7 @@ SQL_TEMPLATES = {
                 SELECT id, 1 - (content_vector <=> '[{embedding_string}]'::vector) as distance
                 FROM LIGHTRAG_DOC_CHUNKS 
                 where workspace=$1
-                AND chunk_id IN (SELECT chunk_id FROM relevant_chunks)
+                AND id IN (SELECT chunk_id FROM relevant_chunks)
             )
             WHERE distance>$2 
             ORDER BY distance DESC