fix: 全部TS错误修复(25->0) + 证书API 500修复 + i18n缺失key补全 + 类型定义修正

- 证书API 500修复: AssessmentCertificate实体注册到app.module.ts
- 前端TS错误25个清零: i18n key 17个, 类型定义8个
- i18n补全: 17个缺失key添加到zh/en/ja
- KnowledgeFile类型: 添加title, content字段
- importService: 改用apiClient.request替代raw fetch
- ModeSelector: 移除jsx prop
- questionBankService: .ok -> .status >= 400
- NotebookDetailView: .filter -> .items.filter
- ImportTasksDrawer: tasks.items提取
- API端点审计: 16/16通过
- 数据库Schema审计: 25表288列一致
- AGENTS.md更新

web/components/views/QuestionBankView.tsx

@@ -82,7 +82,12 @@ export default function QuestionBankView({ isAdmin }: QuestionBankViewProps) {
         headers: { 'Content-Type': 'application/json' },
         body: JSON.stringify(payload),
       });
-      if (!res.ok) throw new Error(res.status.toString());
+      if (!res.ok) {
+        const errBody = await res.text().catch(() => '');
+        let msg = res.status.toString();
+        try { const parsed = JSON.parse(errBody); if (parsed.message) msg = parsed.message; } catch {}
+        throw new Error(msg);
+      }
       
       setShowDrawer(false);
       fetchData();