feat: implement smart foreground quota refresh with debounce

- Trigger immediate quota poll when main window gains focus.
- Add 10s debounce to prevent API spam on frequent window switching.
- Add concurrency guard to prevent overlapping poll requests.
- Reset background polling interval after manual refresh.
- Add unit tests for polling, debounce, and concurrency logic.

src/main.ts

@@ -144,6 +144,10 @@ function createWindow() {
     const { level, message, lineNumber, sourceId } = details;
     logger.info(`[Renderer Console][${level}] ${message} (${sourceId}:${lineNumber})`);
   });
+
+  mainWindow.on('focus', () => {
+    CloudMonitorService.handleAppFocus();
+  });
 }
 
 app.on('child-process-gone', (event, details) => {