Closes#513.
UserDataInitializer reads `@Value("${app.admin.email:...}")` but
application.yaml mapped APP_ADMIN_USERNAME to `app.admin.username`.
The keys never connected — env vars APP_ADMIN_USERNAME and
APP_ADMIN_PASSWORD were silently ignored and the admin user got
seeded with the hardcoded defaults admin@familyarchive.local /
admin123.
For production this is HIGH severity: DEPLOYMENT.md §3.5 documents
the admin password as permanently locked on first deploy. The
bug locked the lock-in to dev defaults, not to whatever an operator
set in PROD_APP_ADMIN_PASSWORD.
Rename yaml key from `username:` to `email:` so the Spring property
`app.admin.email` actually exists. Keep env-var name
APP_ADMIN_USERNAME (matches the already-set Gitea secrets and
DEPLOYMENT.md §3.3). Default value updated to an email-shape.
Added AdminSeedPropertyKeyTest (Binder pattern, no Spring context):
verifies both `app.admin.email` and `app.admin.password` resolve
from the yaml. Confirmed red without the fix, green with it.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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