v2.4.0 — OIDC login, OpenStreetMap search, account management

Features:
- Single Sign-On (OIDC) — login with Google, Apple, Authentik, Keycloak
- OpenStreetMap place search as free fallback when no Google API key
- Change password in user settings
- Delete own account (with last-admin protection)
- Last login column in admin user management
- SSO badge and provider info in user settings
- Google API key "Recommended" badge in admin panel

Improvements:
- API keys load correctly after page reload
- Validate auto-saves keys before testing
- Time format respects 12h/24h setting everywhere
- Dark mode fixes for popups and backup buttons
- Admin stats: removed photos, 4-column layout
- Profile picture upload button on avatar overlay
- TravelStats duplicate key fix
- Backup panel dark mode support

server/src/db/database.js

@@ -250,6 +250,9 @@ function initDb() {
     `ALTER TABLE trips ADD COLUMN is_archived INTEGER DEFAULT 0`,
     `ALTER TABLE categories ADD COLUMN user_id INTEGER REFERENCES users(id) ON DELETE SET NULL`,
     `ALTER TABLE users ADD COLUMN avatar TEXT`,
+    `ALTER TABLE users ADD COLUMN oidc_sub TEXT`,
+    `ALTER TABLE users ADD COLUMN oidc_issuer TEXT`,
+    `ALTER TABLE users ADD COLUMN last_login DATETIME`,
   ];
 
   // Recreate budget_items to allow NULL persons (SQLite can't ALTER NOT NULL)