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/ProjectDetail.vue

@@ -188,7 +188,7 @@
                   <div class="score-bar-track">
                     <div
                       class="score-bar-fill"
-                      :class="dim.score >= 80 ? 'fill-high' : dim.score >= 60 ? 'fill-mid' : 'fill-low'"
+                      :class="'fill-' + scoreTier(dim.score)"
                       :style="{ width: dim.score + '%' }"
                     ></div>
                   </div>
@@ -276,7 +276,7 @@ import { useProjectStore } from '@/stores/project'
 import { projectApi } from '@/api'
 import { formatDate } from '@/utils/time'
 import { parseStack } from '@/utils/project'
-import { parseScores as parseScoresJson, assessmentClass, assessmentLabel as assessmentLabelI18n } from '@/utils/ideaEval'
+import { parseScores as parseScoresJson, assessmentClass, assessmentLabel as assessmentLabelI18n, scoreTier } from '@/utils/ideaEval'
 import { projectStatusLabel, taskStatusLabel, taskStatusClass } from '../constants/project'
 import ConfirmDialog from '@/components/ConfirmDialog.vue'
 import ApprovalDialog from '@/components/project/ApprovalDialog.vue'