Fix: Auto-detect client_id from ClientActivity when not provided in /api/reports/last-sync

- When client doesn't send client_id parameter, look up rustdesk_id from ClientActivity table
- This ensures server uses same client_id that client uses when syncing
- Fixes issue where server derived 'token_66' but client was syncing with '8d95b8a115c19857'
- Server now correctly finds existing sync records and returns requires_full_sync=False

app/api/routes.py

@@ -852,7 +852,7 @@ def track_client_activity(api_token, rustdesk_id=None):
                 db.session.add(client)
                 logger.info(f"track_client_activity: Created new client with rustdesk_id {rustdesk_id}")
         else:
-            # If no rustdesk_id provided, update the most recent client for this API token
+            # If no rustdesk_id provided, update most recent client for this API token
             client = ClientActivity.query.filter_by(
                 api_token_id=api_token.id
             ).order_by(ClientActivity.last_seen.desc()).first()
@@ -999,7 +999,7 @@ def api_reports_sync():
         # Get request data - use force=True to parse JSON even if Content-Type header is missing
         data = request.get_json(force=True, silent=True)
         
-        # Log the full request content for debugging
+        # Log full request content for debugging
         if data:
             logger.info(f"Reports sync request content: {json.dumps(data, indent=2, default=str)}")
         else:
@@ -1094,7 +1094,7 @@ def api_reports_sync():
             }), 400
         
         # Validate summary data
-        summary = data['summary']
+        summary = data.get('summary')
         if not all(key in summary for key in ['total_payin', 'total_payout', 'net_profit', 'total_bets', 'total_matches']):
             return jsonify({
                 'success': False,
@@ -1462,14 +1462,30 @@ def api_get_last_sync():
         
         logger.info(f"API get last sync: user={user.username}, client_id={client_id}, api_token={api_token.name if api_token else 'None'}")
         
-        # If client_id is not provided, derive a unique client_id from the API token
+        # If client_id is not provided, derive it from ClientActivity using API token
         if not client_id:
-            # Use the API token to derive a unique client_id
+            # Get most recent client activity for this API token to find rustdesk_id
             if api_token:
-                # Derive a unique client_id from the API token
-                # This ensures each API token has its own unique client identifier for sync purposes
-                client_id = f"token_{api_token.id}"
-                logger.info(f"API get last sync: Derived client_id={client_id} from API token {api_token.name} (ID: {api_token.id})")
+                most_recent_client = ClientActivity.query.filter_by(api_token_id=api_token.id)\
+                    .order_by(desc(ClientActivity.last_seen))\
+                    .first()
+                
+                if most_recent_client:
+                    client_id = most_recent_client.rustdesk_id
+                    logger.info(f"API get last sync: Auto-detected client_id={client_id} from API token {api_token.name} (ID: {api_token.id}) via ClientActivity")
+                else:
+                    logger.warning(f"API get last sync: No client activity found for API token {api_token.name}")
+                    return jsonify({
+                        'success': True,
+                        'message': 'No client activity found for this API token',
+                        'client_id': None,
+                        'last_sync_id': None,
+                        'last_sync_timestamp': None,
+                        'last_sync_type': None,
+                        'total_syncs': 0,
+                        'requires_full_sync': True,
+                        'server_timestamp': datetime.utcnow().isoformat()
+                    }), 200
             else:
                 logger.warning(f"API get last sync: No API token provided")
                 return jsonify({