Fix Matrix sync ERROR - remove invalid filter configuration

## Bug Fix
- Removed invalid filter configuration that was causing Matrix sync to fail
- Matrix client was throwing 'filter.getDefinition is not a function' error
- Kept optimized sync settings (50 message limit, 30s polling) without filter

## Technical Details
- Matrix-js-sdk expects specific filter object format
- Invalid filter was preventing successful sync initialization
- Now relies on increased sync limits for performance instead of custom filters

## Result
- Matrix sync should now work properly without ERROR state
- Real-time notifications should be faster due to increased limits
- Eliminates the sync failure that was blocking message delivery

Fixes Matrix sync ERROR and improves notification performance

ui/desktop/src/services/MatrixService.ts

@@ -363,13 +363,8 @@ export class MatrixService extends EventEmitter {
     await this.client.startClient({ 
       initialSyncLimit: 50, // Increased from 10 to get more recent messages
       pollTimeout: 30000,   // 30 second long polling for faster notifications
-      filter: {
-        room: {
-          timeline: {
-            limit: 20, // Get more recent messages per room
-          },
-        },
-      },
+      // Remove filter for now - it was causing sync errors
+      // We'll rely on the increased sync limits for better performance
     });
     
     this.syncState = 'SYNCING';