fix: db initialization and vector registration order

server.py

@@ -18,11 +18,15 @@ EMBEDDING_DIM = 768  # BAAI/bge-base-en-v1.5
 mcp = FastMCP("knowledge-mcp")
 
 @contextmanager
-def get_db():
+def get_db(init=False):
     """Provide a database connection."""
     conn = psycopg.connect(DATABASE_URL, autocommit=True)
-    # Register vector type handler
+    # Register vector type handler (skip during init phase before extension exists)
+    if not init:
+        try:
             register_vector(conn)
+        except Exception as e:
+            logging.warning(f"Vector registration failed (ignoring if init): {e}")
     try:
         yield conn
     finally:
@@ -31,9 +35,13 @@ def get_db():
 def init_db():
     """Initialize database schema."""
     try:
-        with get_db() as conn:
+        # Pass init=True to skip vector registration before extension exists
+        with get_db(init=True) as conn:
             conn.execute("CREATE EXTENSION IF NOT EXISTS vector")
             
+            # Now we can register it for the rest of the session if we wanted, 
+            # but for this function we just need to create tables.
+            
             # Notebooks table (simple registry)
             conn.execute("""
                 CREATE TABLE IF NOT EXISTS notebooks (