feat: 书库导入导出/图片变体/书籍搜索/小组件运行时等

新增：
- 书库导入导出（library_import/library_export）及测试
- 图片变体生成（image_variants）与响应式图片（responsiveImage）
- 书籍搜索（bookSearch）+ BookSearch/LibrarySearchGrid 组件
- 小组件运行时（widgetRuntime）与静态检查（widgetLint）
- 上传缓存中间件（upload_cache）与字体 CSS 提取脚本

其它：
- 后端 handlers/services 全量调整
- 前端页面、组件、库函数与配置更新

frontend/lib/jsonLd.test.ts

@@ -33,16 +33,18 @@ describe("questionJsonLd", () => {
       createdAt: "2026-09-01T00:00:00Z",
       author: { id: 3, name: "甲" },
       postId: 9,
-      accepted: { id: 4, content: "用索引", created_at: "2026-09-02T00:00:00Z", author: { id: 5, name: "乙" } },
+      accepted: { id: 4, floor: 1, content: "用索引", created_at: "2026-09-02T00:00:00Z", author: { id: 5, name: "乙" } },
       answers: [
-        { id: 4, content: "用索引", created_at: "2026-09-02T00:00:00Z", author: { id: 5, name: "乙" } },
-        { id: 6, content: "先 EXPLAIN", created_at: "2026-09-03T00:00:00Z" },
+        { id: 4, floor: 1, content: "用索引", created_at: "2026-09-02T00:00:00Z", author: { id: 5, name: "乙" } },
+        { id: 6, floor: 2, content: "先 EXPLAIN", created_at: "2026-09-03T00:00:00Z" },
       ],
     });
     assert.ok(data);
-    const q = data.mainEntity as { acceptedAnswer: { text: string }; suggestedAnswer: { text: string }[] };
+    const q = data.mainEntity as { acceptedAnswer: { text: string; url: string }; suggestedAnswer: { text: string; url: string }[] };
     assert.equal(q.acceptedAnswer.text, "用索引");
+    assert.equal(q.acceptedAnswer.url, "https://bbs.example.com/post/9#comment-1");
     assert.deepEqual(q.suggestedAnswer.map((a) => a.text), ["先 EXPLAIN"]);
+    assert.equal(q.suggestedAnswer[0].url, "https://bbs.example.com/post/9#comment-2");
     assert.equal(data["@type"], "QAPage");
   });
 });
@@ -57,11 +59,13 @@ describe("discussionJsonLd", () => {
       author: { id: 1, name: "丙" },
       postId: 8,
       pageUrl: "https://bbs.example.com/post/8?page=2",
-      comments: [{ id: 2, content: "可见楼层", created_at: "2026-09-01T01:00:00Z" }],
+      comments: [{ id: 2, floor: 21, content: "可见楼层", created_at: "2026-09-01T01:00:00Z" }],
     });
     assert.equal(data?.url, "https://bbs.example.com/post/8");
     const page = data?.mainEntityOfPage as { url: string };
     assert.equal(page.url, "https://bbs.example.com/post/8?page=2");
-    assert.equal((data?.comment as { text: string }[])[0].text, "可见楼层");
+    const firstComment = (data?.comment as { text: string; url: string }[])[0];
+    assert.equal(firstComment.text, "可见楼层");
+    assert.equal(firstComment.url, "https://bbs.example.com/post/8#comment-21");
   });
 });