Add NextSnap PWA with photo gallery viewer and continuous capture

Offline-first photo capture app for Nextcloud with:
- Camera capture with continuous mode (auto-reopens after each photo)
- File browser with fullscreen image gallery, swipe navigation, and rename
- Upload queue with background sync engine
- Admin panel for Nextcloud user management
- Service worker for offline-first caching (v13)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/routes/health.py

@@ -0,0 +1,35 @@
+from flask import Blueprint, jsonify
+import requests
+from config import Config
+
+bp = Blueprint('health', __name__, url_prefix='/api')
+
+@bp.route('/health', methods=['GET'])
+def health_check():
+    """Health check endpoint for monitoring."""
+    return jsonify({
+        'status': 'healthy',
+        'service': 'nextsnap',
+        'version': '1.0.0'
+    }), 200
+
+@bp.route('/health/nextcloud', methods=['GET'])
+def nextcloud_health():
+    """Check connectivity to Nextcloud instance."""
+    try:
+        nc_url = Config.NEXTCLOUD_URL
+        response = requests.get(f"{nc_url}/status.php", timeout=5)
+        response.raise_for_status()
+        
+        return jsonify({
+            'status': 'healthy',
+            'nextcloud_url': nc_url,
+            'nextcloud_reachable': True
+        }), 200
+    except Exception as e:
+        return jsonify({
+            'status': 'degraded',
+            'nextcloud_url': Config.NEXTCLOUD_URL,
+            'nextcloud_reachable': False,
+            'error': str(e)
+        }), 503