重构: 前端DRY收口+后端测试类型对齐

- 新增 useToast composable: 消除 AiChat/Settings/Projects 4处 toast 重复
  统一默认3000ms(Projects原4000ms为操作类提示保留参数覆盖)
- 新增 utils/json.ts parseJsonArray: 消除 parseStack/parseTags/ModuleNode
  3处JSON字符串数组解析重复
- 新增 utils/html.ts escapeHtml: 消除 useMarkdown/FilePreview 2处重复
- ProjectDetail score-bar 内联三元改用 scoreTier(消除最后一处阈值硬编码)
- ConversationSidebar 删除 formatTime 透传包装(直接用 formatRelative)
- 清理死代码: parseTs/stringifyError/ErrorSink/_Unused 改私有或删除
  wrapNakedDiff 改私有(无外部 import)
- ModuleNode shortPath 改名 truncatedPath(与 useToolCard.shortPath 语义不同)

src/views/Settings.vue

@@ -67,8 +67,9 @@
 </template>
 
 <script setup lang="ts">
-import { computed, reactive, ref, shallowRef, onMounted, onUnmounted, nextTick } from 'vue'
+import { computed, ref, shallowRef, onMounted, onUnmounted, nextTick } from 'vue'
 import { useConfirm } from '@/composables/useConfirm'
+import { useToast } from '@/composables/useToast'
 import ConfirmDialog from '@/components/ConfirmDialog.vue'
 import SettingsNav, { type SettingsCategory } from '@/components/settings/SettingsNav.vue'
 import ProviderPanel from '@/components/settings/ProviderPanel.vue'
@@ -90,17 +91,8 @@ import { t as ti18n } from '@/i18n/i18n-helpers'
 // (阶段3 UX 重构:左导航 + 右按 activeCategory 渲染,各功能域 state/methods 已拆到子组件)
 // ============================================================
 
-// 顶部轻量提示（错误/警告/完成），3s 自动消失；零依赖，替代未接入的 Arco Message
-const toast = reactive({ visible: false, msg: '', type: 'info' as 'error' | 'warning' | 'info' })
-let _toastTimer: ReturnType<typeof setTimeout> | null = null
-
-function showToast(msg: string, type: 'error' | 'warning' | 'info' = 'info') {
-  toast.msg = msg
-  toast.type = type
-  toast.visible = true
-  if (_toastTimer) clearTimeout(_toastTimer)
-  _toastTimer = setTimeout(() => { toast.visible = false }, 3000)
-}
+// 顶部轻量提示(useToast composable,消除 4 处重复;默认 3000ms)
+const { toast, showToast } = useToast()
 
 // 确认弹层状态机抽至 composables/useConfirm(原 4 视图重复:Projects/ProjectDetail/Ideas/Settings)
 // 模板 confirmState.visible/msg 在 <script setup> 中自动解包 ref,沿用既有内联确认弹层
@@ -207,9 +199,8 @@ onMounted(() => {
   void loadAiProviders()
 })
 
-// 组件卸载清 toast/resize timer;各子面板自管自身 debounce timer(各自 onUnmounted)
+// 组件卸载清 resize timer;toast 清理由 useToast 自动管理;各子面板自管自身 debounce timer
 onUnmounted(() => {
-  if (_toastTimer) clearTimeout(_toastTimer)
   if (_resizeTimer) clearTimeout(_resizeTimer)
   window.removeEventListener('resize', onResize)
   providerPanelRef.value?.clearPoolTimer()