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>
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