- Extract shared route_utils.py (validate_symbol, safe decorator)
removing duplication from 6 route files
- Extract shared obb_utils.py (to_list, extract_single, safe_last)
removing duplication from calendar_service and market_service
- Fix _to_list dict mutation during iteration (use comprehension)
- Fix double vars() call and live __dict__ mutation risk
- Fix route ordering: /etf/search and /crypto/search now registered
before /{symbol} path params to prevent shadowing
- Add date format validation (YYYY-MM-DD pattern) on calendar routes
- Use timezone-aware datetime.now(tz=timezone.utc) in all services
- Add explicit type annotation for asyncio.gather results
