fix(sync): corrige event name force-sync → sync-request no trigger-sync

O servidor emitia 'force-sync' mas o client-monitor.js só ouve
'sync-request'. O botão Sincronizar do painel nunca chegava ao cliente.

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

dental-server/server.js

@@ -295,7 +295,7 @@ app.post('/api/system/trigger-sync', authenticateToken, requireAdmin, (req, res)
     identifiedWindowsClients.forEach(client => {
       const socket = io.sockets.sockets.get(client.socketId);
       if (socket) {
-        socket.emit('force-sync');
+        socket.emit('sync-request', { timestamp: Date.now() });
         devicesTriggered++;
       }
     });