#43 Fix all mypy type errors in API and engine files

Fix mypy type errors in: api/fix_logging.py, api/replace_console_logs.py, api/oauth_handlers/oauth2.py, api/migrate_to_appstate.py, api/app.py, engine/cli/monitor_steps.py, engine/cli/scheduler_worker.py, engine/cli/submit.py, engine/cli/monitor.py, engine/cli/showlogs.py, engine/cli/login.py, engine/cli/worker.py, engine/durable_context.py, engine/utils/event_logger.py, engine/orchestrator.py. Only add type annotations, no logic changes.