修复: i18n 裸 @ 致生产环境对话输入框消失

- 905 将 @ 改为裸 @,而 vue-i18n 的 @ 是 linked-message 语法字符,未转义只在 prod runtime 抛 Invalid linked format(dev 宽松回退/vue-tsc 捕获不到)
- zh/en aiChat 8 处(placeholderDefault/mentionHint/searchFilesBlocked/projectLabel)按规范转义为 {'@'}
- 输入框 placeholder 消息编译抛错→ChatInput 渲染失败→输入框消失,即本次生产回归根因
- 验证: 全库 462 个含 @/{/| 的 i18n 值经 message-compiler 编译 0 失败 + vue-tsc EXIT 0

src/i18n/en/aiChat.ts

@@ -137,12 +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',
@@ -233,7 +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)
@@ -327,7 +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 ──

src/i18n/zh-CN/aiChat.ts

@@ -137,12 +137,12 @@ export default {
     clearSkill: '取消技能',
     skillBadgeTip: '已注入技能「{name}」的完整规程',
     placeholderWithSkill: '已选技能，输入参数后回车',
-    placeholderDefault: "输入消息...（/ 触发技能，@ 引用实体）",
+    placeholderDefault: "输入消息...（/ 触发技能，{'@'} 引用实体）",
     skillNoMatch: '无匹配技能',
     skillNotLoaded: '未读取到本机技能',
 
     // ── @ 实体引用(@ 触发 popover,选中插入 [类型:名] 标记) ──
-    mentionHint: "@ 引用项目/任务",
+    mentionHint: "{'@'} 引用项目/任务",
     mentionGroupProject: '项目',
     mentionGroupTask: '任务',
     mentionGroupIdea: '灵感',
@@ -234,7 +234,7 @@ export default {
 
     // ── Input Augmentation 层: mention/skill 注入反馈 ──
     // search_files 盲搜被白名单兜底拒绝(不应弹授权窗,直接友好提示用户改用 @引用或绝对路径)
-    searchFilesBlocked: "search_files 仅在已授权目录可用,请用 @[项目] 引用或提供绝对路径",
+    searchFilesBlocked: "search_files 仅在已授权目录可用,请用 {'@'}[项目] 引用或提供绝对路径",
     // /技能 热重载(ai_reload_skills IPC)成功后提示
     skillReloaded: '技能已重新加载',
     // @引用 实体 resolve 失败(id 指向的项目/任务/灵感/技能已被删除或不可用)
@@ -328,7 +328,7 @@ export default {
     // ── TopBar 目标/项目上下文标签 ──
     goalsCount: '目标({n})',
     none: '无',
-    projectLabel: "@项目",
+    projectLabel: "{'@'}项目",
 
     // ── 3c UX 批追加(I5 发送失败错误分类文案):按错误内容映射友好提示,
     //    {msg} 保留原始错误串供排查,不丢线索 ──