feat(webui): add Tailwind build system and refactor frontend architecture

- Replace Tailwind CDN with local build (PostCSS + autoprefixer + daisyui)

- Add CSS build scripts with automatic prepare hook on npm install

- Create account-actions.js service layer with unified response format

- Extend ErrorHandler.withLoading() for automatic loading state management

- Add skeleton screens for initial load, silent refresh for subsequent updates

- Implement loading animations for async operations (buttons, modals)

- Improve empty states and add ARIA labels for accessibility

- Abstract component styles using @apply (buttons, badges, inputs)

- Add JSDoc documentation for Dashboard modules

- Update README and CLAUDE.md with development guidelines

public/js/components/dashboard/stats.js

@@ -1,12 +1,37 @@
 /**
  * Dashboard Stats Module
- * Handles account statistics calculation
+ * 职责：根据 Alpine.store('data') 计算账号统计数据
+ *
+ * 调用时机：
+ *   - dashboard 组件 init() 时
+ *   - $store.data 更新时（通过 $watch 监听）
+ *
+ * 统计维度：
+ *   - total: 启用账号总数（排除禁用账号）
+ *   - active: 有可用配额的账号数
+ *   - limited: 配额受限或失效的账号数
+ *   - subscription: 按订阅级别分类（ultra/pro/free）
+ *
+ * @module DashboardStats
  */
 window.DashboardStats = window.DashboardStats || {};
 
 /**
- * Update account statistics (active, limited, total)
- * @param {object} component - Dashboard component instance
+ * 更新账号统计数据
+ *
+ * 统计逻辑：
+ *   1. 仅统计启用的账号（enabled !== false）
+ *   2. 优先统计核心模型（Sonnet/Opus/Pro/Flash）的配额
+ *   3. 配额 > 5% 视为 active，否则为 limited
+ *   4. 状态非 'ok' 的账号归为 limited
+ *
+ * @param {object} component - Dashboard 组件实例（Alpine.js 上下文）
+ * @param {object} component.stats - 统计数据对象（会被修改）
+ * @param {number} component.stats.total - 启用账号总数
+ * @param {number} component.stats.active - 活跃账号数
+ * @param {number} component.stats.limited - 受限账号数
+ * @param {object} component.stats.subscription - 订阅级别分布
+ * @returns {void}
  */
 window.DashboardStats.updateStats = function(component) {
     const accounts = Alpine.store('data').accounts;