Wraps the deprecated global `db = engine.connect()` in a try/except so
a Docker startup race (MariaDB not yet ready) no longer crashes the
Gunicorn worker before it can serve any requests.
Sets db=None on failure; reconnect_db() on the lifespan bootstrap path
re-establishes it once credentials are confirmed.
TODO (P3 full): migrate lib_schema_v3.py:39 and lib_api_crud_v3.py:166
off the global db to engine.connect() context managers, then remove it.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
- Refactor SQL CRUD to use engine.connect() context managers for thread safety
- Optimize connection pooling in lib_sql_core
- Clean up app/routers/api.py to fix duplicate definitions and OpenAPI KeyError
- Add 'default_qry_str' to searchable_fields for Event, Session, Presentation, Presenter, Badge, and Journal
- Add 'event_location_name' to searchable_fields for Event Session
- Verified 20/20 E2E success via repro_intermittent_errors.py
- Update sql_connect to refresh global db object via reconnect_db
- Add returns_rows check and safe fetch block in sql_select
- Prevents 500 errors during transient database connection issues
