feat: add account management, email verification, AI fixes, and user guides

- Profile settings, account transfer, delete/leave account flows
- Email verification with JWT tokens and Resend integration
- AI assistant/copilot fixes: markdown rendering, shared RAG helpers,
  token tracking, input refocus, model_validate usage
- User guides hub + detail pages with 13 topic guides
- Sidebar and top bar navigation for guides

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/vite.config.ts

@@ -6,6 +6,12 @@ import path from 'path'
 // https://vite.dev/config/
 export default defineConfig({
   plugins: [react()],
+  server: {
+    host: '0.0.0.0',
+    watch: {
+      usePolling: true,
+    },
+  },
   resolve: {
     alias: {
       '@': path.resolve(__dirname, './src'),