The Apple Calendar sync hardcoded created_by=1 which fails when no user
with ID 1 exists, causing every single event import to fail silently.
Now dynamically resolves the first available user. Also syncs all
calendars instead of only the first one, adds the missing cfgDel helper,
and gracefully skips unreachable calendars.
Fixes#4
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Admin can now enter CalDAV URL, Apple-ID and app-specific password
directly in Settings; credentials are tested live before saving and
stored in sync_config (take precedence over .env); disconnect clears
DB-stored credentials without server restart. Auto-sync interval
(15 min, configurable via SYNC_INTERVAL_MINUTES) was already in place.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>