infra: add linting and formatting for js projects (#230)

* wip

* wip

* wip

* format

* wip(mobile): lint and format

* cleanup

* nits

* nits

* idiomatic react

* nit

* format all root files

js/desktop/src/screen_record_window/ScreenRecordControlApp.tsx

@@ -1,5 +1,5 @@
-import { useCallback, useEffect, useState } from "react";
-import { Square } from "lucide-react";
+import { useCallback, useEffect, useState } from 'react';
+import { Square } from 'lucide-react';
 
 export function ScreenRecordControlApp() {
   const [elapsed, setElapsed] = useState(0);
@@ -12,7 +12,7 @@ export function ScreenRecordControlApp() {
 
   const minutes = Math.floor(elapsed / 60);
   const seconds = elapsed % 60;
-  const display = `${minutes}:${seconds.toString().padStart(2, "0")}`;
+  const display = `${minutes}:${seconds.toString().padStart(2, '0')}`;
 
   const handleStop = useCallback(() => {
     window.electronScreenRecord.stop();

js/desktop/src/screen_record_window/renderer.tsx

@@ -5,5 +5,7 @@ import '@/styles/globals.css';
 
 initSentryRenderer();
 
-const root = createRoot(document.getElementById('root')!);
+const container = document.getElementById('root');
+if (!container) throw new Error('Root element #root not found');
+const root = createRoot(container);
 root.render(<ScreenRecordControlApp />);