初始提交：姜十三论坛 Jiang13 Forum

轻量自用论坛，Go 单二进制 + React SPA 内嵌 + SQLite。

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/main.tsx

@@ -0,0 +1,12 @@
+import React from 'react';
+import ReactDOM from 'react-dom/client';
+import { applyTheme, getStoredTheme } from './utils/theme';
+import App from './App';
+
+applyTheme(getStoredTheme());
+
+ReactDOM.createRoot(document.getElementById('root')!).render(
+  <React.StrictMode>
+    <App />
+  </React.StrictMode>
+);