App-level logs (logging.getLogger("app.*")) had no StreamHandler, so their
INFO was lost — `docker logs gendesign-backend-1` showed only uvicorn loggers.
Useful lines (e.g. "OSRM road-distance applied", RBAC, analyze) were invisible
when debugging on the VPS (only Sentry/GlitchTip received them as breadcrumbs).
main.py now attaches one StreamHandler to the root "app" logger at
APP_LOG_LEVEL (default INFO), idempotent (marker guard), propagate=True so the
Sentry LoggingIntegration on root still gets breadcrumbs/events and there's no
stdout double (root has no stdout handler). API process only — celery worker
(celery_app.py) untouched, since its loaders log per-sync and would be noisy.
Flood-safe on the API: the analyze hot path logs INFO per-request (parcels.py
has 3 logger.info), not per-row.
Adds tests/test_app_logging.py (handler present, level INFO, propagate intact).
Refs #1926
