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

client/src/store/authStore.js

@@ -9,6 +9,7 @@ export const useAuthStore = create((set, get) => ({
   isLoading: false,
   error: null,
   demoMode: localStorage.getItem('demo_mode') === 'true',
+  hasMapsKey: false,
 
   login: async (email, password) => {
     set({ isLoading: true, error: null })
@@ -137,6 +138,8 @@ export const useAuthStore = create((set, get) => ({
     set({ demoMode: val })
   },
 
+  setHasMapsKey: (val) => set({ hasMapsKey: val }),
+
   demoLogin: async () => {
     set({ isLoading: true, error: null })
     try {