fix: parse JSON theme value from localStorage in index.html (#233)

- localStorage stores theme as JSON string ("dark") via setStorageItem
- index.html was comparing with raw string causing theme mismatch
- Added JSON.parse with error handling for proper theme initialization

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-authored-by: Claude <noreply@anthropic.com>

Author: sugyan

frontend/index.html

@@ -8,7 +8,15 @@
     <script>
       // Prevent flash of unstyled content by setting theme class early
       (function () {
-        const theme = localStorage.getItem("claude-code-webui-theme");
+        const storedTheme = localStorage.getItem("claude-code-webui-theme");
+        let theme = null;
+        try {
+          theme = storedTheme ? JSON.parse(storedTheme) : null;
+        } catch {
+          // If parsing fails, fall back to null
+          theme = null;
+        }
+        
         if (
           theme === "dark" ||
           (!theme && window.matchMedia("(prefers-color-scheme: dark)").matches)