feat: 新增第 8 个内置 tab「文件追踪」——移植 dsh-file-trace 插件

- 数据层：直接折叠会话事件日志(tool/call + tool/result 对)提取文件操作，
  与仓库「读事件日志而非动注册表」的取向一致；含错误文本捕获与
  running 态实时更新(ctx.on('session/event')，不可见时暂停、恢复时追平)
- 视图：操作列表 + 底部可拖拽 diff 面板；行级 diff(删红/增绿/改蓝)+
  行内字符级高亮；读取视图带真实行号；失败操作统一展示真实错误文本
- 语法着色：轻量分词器(关键字/字符串/数字/类型/函数/注释/预处理)，
  色相经 color-mix 落在 diff 三色之间的空档；跨行块注释状态按行序推导
- 单实例 tab，+ 菜单 order 55，角标显示操作数；设置页可整体关闭
  (与独立维护的 dsh-file-trace 插件共存)
- i18n：10 个新 key 同步全部 21 个词典；builtins 测试 7→8；
  README/指南内置清单同步

src/client/builtins/tabs.tsx

@@ -1,6 +1,7 @@
 /**
- * The 7 built-in tab descriptors: the plugin registers its own pages
- * (editor / git / subagent / sidechat / terminal / browser / diff) through
+ * The 8 built-in tab descriptors: the plugin registers its own pages
+ * (editor / git / subagent / sidechat / terminal / browser / diff /
+ * file-trace) through
  * the same {@link BetterSidebarService} external plugins use — eating its
  * own dogfood. The terminal descriptor owns its quota (`TERMINAL_LIMIT`)
  * and mints `terminal:<uuid>` ids through `createTab`; the browser mints
@@ -21,7 +22,9 @@ import { SubagentView } from '../SubagentView.tsx'
 import { consumeSidechatSeed, SideChatView, sidechatThreadIdOf } from '../SideChatView.tsx'
 import { api } from '../api.ts'
 import { BrowserView } from '../BrowserView.tsx'
-import { IconTerminalOutline16, IconDiffOutline16, IconGlobeOutline16 } from '../icons.tsx'
+import { IconTerminalOutline16, IconDiffOutline16, IconGlobeOutline16, IconHistoryOutline16 } from '../icons.tsx'
+import { FileTraceTab } from '../filetrace/FileTraceTab.tsx'
+import { extractFileOps } from '../filetrace/ops.ts'
 import { TERMINAL_FONT_SIZE_MAX, TERMINAL_FONT_SIZE_MIN } from '../../prefs-shared.ts'
 import type { ComponentType } from 'react'
 import type { SessionScope } from '../api.ts'
@@ -335,6 +338,18 @@ export function builtinTabs(ctx: Context, options: BuiltinTabOptions = {}): read
       }),
       component: (props) => <BrowserView {...props} />,
     },
+    {
+      id: 'file-trace',
+      title: () => t('fileTrace'),
+      icon: (size: number) => <IconHistoryOutline16 size={size} />,
+      order: 55,
+      single: true,
+      badge: (ctx, scope) => {
+        const events = ctx.sessions.get(scope.sessionId)?.events
+        return events === undefined ? null : extractFileOps(events).length
+      },
+      component: (props) => <FileTraceTab {...props} />,
+    },
     {
       id: 'diff',
       title: () => t('git'),