refac: modernize imports, standardize type hints and docstrings

backend/open_webui/migrations/env.py

@@ -9,12 +9,11 @@ import logging
 from logging.config import fileConfig
 
 from alembic import context
-from sqlalchemy import create_engine, engine_from_config, pool
-
 from open_webui.env import DATABASE_PASSWORD, DATABASE_URL, LOG_FORMAT
 from open_webui.internal.db import extract_ssl_params_from_url, reattach_ssl_params_to_url
 from open_webui.models.auths import Auth
 from open_webui.models.calendar import Calendar, CalendarEvent, CalendarEventAttendee  # noqa: F401
+from sqlalchemy import create_engine, engine_from_config, pool
 
 # ── Alembic config & logging ─────────────────────────────────────────────────
 

backend/open_webui/migrations/util.py

@@ -1,14 +1,13 @@
 """Alembic migration utilities."""
 
 from alembic import op
-from sqlalchemy import inspect as sa_inspect
+from sqlalchemy import inspect
 
 
 def get_existing_tables() -> set[str]:
-    """Return the set of table names already present in the database."""
-    bind = op.get_bind()
-    inspector = sa_inspect(bind)
-    return set(inspector.get_table_names())
+    """Return table names already present in the database."""
+    conn = op.get_bind()
+    return set(inspect(conn).get_table_names())
 
 
 def get_revision_id() -> str: