Fix status indicator not syncing when switching tables

Reset isConnected and isBackendConnected to false when switching tables
so the header status indicator shows the transitional state until the
new table's WebSocket connection reports its actual status.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/components/layout/Layout.tsx

@@ -283,6 +283,8 @@ export function Layout() {
     const unsubscribe = apiClient.onBaseUrlChange(() => {
       if (isMounted) {
         wasPlayingRef.current = null // Reset playing state for new table
+        setIsConnected(false) // Reset connection status until new table reports
+        setIsBackendConnected(false) // Show connecting state
         connectWebSocket()
       }
     })