build: update frontend asset references in index.html and add it to .gitignore.

.gitignore

@@ -76,3 +76,4 @@ goclaw.db-shm
 
 # Auto-generated by Makefile (git describe)
 VERSION
+ui/desktop/frontend/dist/index.html

ui/desktop/frontend/dist/index.html

@@ -1,22 +0,0 @@
-<!DOCTYPE html>
-<html lang="en" class="dark">
-<head>
-  <meta charset="UTF-8" />
-  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
-  <title>GoClaw</title>
-  <script>
-    // Apply persisted theme before first paint to prevent flash
-    try {
-      const stored = JSON.parse(localStorage.getItem('goclaw-ui') || '{}')
-      if (stored.state?.theme === 'light') {
-        document.documentElement.classList.remove('dark')
-      }
-    } catch {}
-  </script>
-  <script type="module" crossorigin src="/assets/index-COTE9Ugk.js"></script>
-  <link rel="stylesheet" crossorigin href="/assets/index-D6czDNCk.css">
-</head>
-<body>
-  <div id="root"></div>
-</body>
-</html>