fix(vector): harden packaged migrations

harness/tests/l0/test_pgvector_store.py

@@ -45,8 +45,8 @@ def vector_configs():
         )
         engine = create_engine(pg.get_connection_url())
         with engine.begin() as connection:
-            connection.exec_driver_sql("CREATE EXTENSION vector")
             connection.exec_driver_sql("CREATE SCHEMA vectors")
+            connection.exec_driver_sql("CREATE EXTENSION vector WITH SCHEMA vectors")
             for table in ("schema_records", "evidence", "memory"):
                 connection.exec_driver_sql(f"""
                     CREATE TABLE vectors.{table} (
@@ -55,7 +55,7 @@ def vector_configs():
                         kind text NOT NULL,
                         content_hash text NOT NULL,
                         metadata jsonb NOT NULL,
-                        embedding vector(2) NOT NULL,
+                        embedding vectors.vector(2) NOT NULL,
                         indexed_at timestamptz NOT NULL DEFAULT now()
                     )
                 """)