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 ─────────────────────────────────────────────────