- Added encryption key configuration section in admin payment settings page
- Encryption key can now be set/viewed in admin UI instead of only env var
- Key is stored in admin_settings table with get/save methods in database.py
- Startup loads key from: 1) database, 2) environment, 3) generates temporary
- Added API endpoints: GET/POST /api/admin/settings/encryption-key
- UI shows key status (database/environment/temporary) and allows generation
- Includes security warnings about not changing key after master keys generated
- Fixes issue where temporary key was regenerated on every restart