优化: AI Chat 消息视图: 闪烁修复+骨架统一+过程卡降级+任务关联 chip

MessageList.vue:
1. 流式闪烁修复: _mdRenderKey 稳定化 + key 对齐, 消除流式重渲染抖动
2. 骨架统一: 过程步骤卡改用 trace 卡骨架(头部一行摘要 + 正文增量)
3. 过程卡视觉降级: 缩进收窄 + 紧贴结果, 弱化过程突出结论
4. 消息任务关联: TASK_REF_TOOLS 映射(advance_task/run_workflow) 从
   toolCalls[].args 派生任务 chip, 零数据模型改动(单一事实源), 无任务工具
   的消息不渲染 chip; 新增 .ai-trace-task-chip 样式 + go-to-task emit

AiChat.vue: goToTask(taskId) 接参, router.push('/tasks?taskId=xxx')
Tasks.vue: applyRouteTaskId 消费 query.taskId 自动开抽屉(onMounted 跨路由 +
  watch 同路由), 消费后 router.replace 清 query 保持 URL 干净
i18n zh/en: aiChat.goToTaskHint + ai.trace.taskRef 双语补键

验收: vue-tsc --noEmit EXIT 0 + build EXIT 0。

src/i18n/en/aiChat.ts

@@ -113,6 +113,7 @@ export default {
     examplePrompt4: 'Generate a project idea',
     goToSettings: 'Open settings',
     goToSettingsHint: 'The detached window cannot open settings directly. Configure AI providers on the main window’s Settings page.',
+    goToTaskHint: 'The detached window cannot open tasks directly. View task details in the main window.',
 
     // ── Provider switch feedback ──
     providerSwitched: 'Switched to {model}',
@@ -136,12 +137,12 @@ export default {
     clearSkill: 'Clear skill',
     skillBadgeTip: 'Injected full skill playbook: {name}',
     placeholderWithSkill: 'Skill selected. Type arguments and press Enter',
-    placeholderDefault: "Type a message... (/ for skills, @ to mention)",
+    placeholderDefault: "Type a message... (/ for skills, @ to mention)",
     skillNoMatch: 'No matching skill',
     skillNotLoaded: 'No local skills loaded',
 
     // ── @ entity mention (@ opens popover, select inserts [Type:Name] token) ──
-    mentionHint: "@ to mention project/task",
+    mentionHint: "@ to mention project/task",
     mentionGroupProject: 'Projects',
     mentionGroupTask: 'Tasks',
     mentionGroupIdea: 'Ideas',
@@ -232,7 +233,7 @@ export default {
 
     // ── Input Augmentation layer: mention/skill injection feedback ──
     // search_files blind search denied by whitelist fallback (no auth dialog; prompt user to use @mention or absolute path)
-    searchFilesBlocked: "search_files only works inside authorized dirs. Use @[project] to reference or provide an absolute path.",
+    searchFilesBlocked: "search_files only works inside authorized dirs. Use @[project] to reference or provide an absolute path.",
     // /skill hot reload (ai_reload_skills IPC) success toast
     skillReloaded: 'Skills reloaded',
     // @mention entity resolve failed (id points to a project/task/idea/skill that was deleted or unavailable)
@@ -326,7 +327,7 @@ export default {
     // ── TopBar goal/project context labels ──
     goalsCount: 'Goals ({n})',
     none: 'None',
-    projectLabel: "@Projects",
+    projectLabel: "@Projects",
 
     // ── 3c UX batch addition (I5 classified send-failure messages): friendly text by
     //    error kind; {msg} keeps the raw error string for troubleshooting ──