feat: add usage statistics page, CLI improvements, and UI enhancements

- Add Usage Stats page with token breakdown, model distribution, and 30-day trend
- Pass through cache/cost token fields in BFF (cache_read/write_tokens, reasoning_tokens, actual_cost_usd)
- Add CLI commands: -v/--version, -h/--help, update/upgrade with auto-restart
- Auto-open browser on startup, auto-kill port conflicts (cross-platform)
- Validate all api_server config fields on startup (enabled, host, port, key, cors_origins)
- Add streaming thinking video animation with tool calls panel
- Add context token usage display (used / total) in chat header
- Sidebar: white logo area with shadow, dance video beside logo (canvas seamless loop)
- Fix sidebar nav scroll (app-main overflow-y: auto)

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

src/i18n/locales/zh.ts

@@ -30,6 +30,7 @@ export default {
     skills: '技能',
     memory: '记忆',
     logs: '日志',
+    usage: '用量',
     channels: '频道',
     settings: '设置',
     connected: '已连接',
@@ -43,6 +44,7 @@ export default {
     attachFiles: '添加附件',
     stop: '停止',
     send: '发送',
+    contextUsed: '上下文已用:',
     sessions: '会话',
     noSessions: '暂无会话',
     newChat: '新建对话',
@@ -337,4 +339,25 @@ export default {
     zh: '中文',
     en: 'English',
   },
+
+  // 用量统计
+  usage: {
+    title: '用量统计',
+    refresh: '刷新',
+    totalTokens: '总 Token 数',
+    inputTokens: '输入',
+    outputTokens: '输出',
+    totalSessions: '总会话数',
+    avgPerDay: '日均 ~{n}',
+    estimatedCost: '预估费用',
+    cacheHitRate: '缓存命中率',
+    modelBreakdown: '模型分布',
+    dailyTrend: '每日用量（近 30 天）',
+    date: '日期',
+    tokens: 'Token',
+    cache: '缓存',
+    sessions: '会话',
+    cost: '费用',
+    noData: '暂无用量数据',
+  },
 }