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

README.md

@@ -28,7 +28,8 @@ A self-hosted, real-time collaborative travel planner for organizing trips with
 
 - **Real-Time Collaboration** — Plan together via WebSocket live sync — changes appear instantly across all connected users
 - **Interactive Map** — Leaflet map with marker clustering, route visualization, and customizable tile sources
-- **Google Places Integration** — Search places, auto-fill details including ratings, reviews, opening hours, and photos (requires API key)
+- **Place Search** — Search via Google Places (with photos, ratings, opening hours) or OpenStreetMap (free, no API key needed)
+- **Single Sign-On (OIDC)** — Login with Google, Apple, Authentik, Keycloak, or any OIDC provider
 - **Drag & Drop Planner** — Organize places into day plans with reordering and cross-day moves
 - **Weather Forecasts** — Current weather and 5-day forecasts with smart caching (requires API key)
 - **Budget Tracking** — Category-based expenses with pie chart, per-person/per-day splitting, and multi-currency support