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

backend/service/media_library.go

@@ -30,6 +30,27 @@ var mediaLibraryCategories = []struct {
 	{"brand", "brand", "品牌资源"},
 }
 
+// 衍生分类：不对应 uploads 子目录，按附件 source 归类
+const (
+	mediaCategoryBook     = "book"
+	mediaCategoryBookName = "书籍"
+)
+
+// mediaCategoryForAttachment 附件在媒体库中的展示分类：
+// 书库封面 / 正文插图（source=library_cover|library_content）统一归“书籍”，
+// 其余按 kind 对应磁盘目录分类。
+func mediaCategoryForAttachment(kind, source string) (key, name string) {
+	if source == model.AttachmentSourceLibraryCover || source == model.AttachmentSourceLibraryContent {
+		return mediaCategoryBook, mediaCategoryBookName
+	}
+	for _, cat := range mediaLibraryCategories {
+		if cat.Key == kind {
+			return cat.Key, cat.Name
+		}
+	}
+	return kind, kind
+}
+
 // MediaLibraryItem 媒体库条目
 type MediaLibraryItem struct {
 	URL          string     `json:"url"`                    // 展示地址（有 WebP 时为 WebP）
@@ -53,6 +74,7 @@ func (s *UploadService) AdminMediaLibrary() ([]MediaLibraryItem, map[string]int,
 	// 附件元数据索引：URL → 记录（联出上传者昵称）
 	type attMeta struct {
 		Kind      string
+		Source    string
 		URL       string
 		MIME      string
 		Size      int
@@ -64,7 +86,7 @@ func (s *UploadService) AdminMediaLibrary() ([]MediaLibraryItem, map[string]int,
 	}
 	var rows []attMeta
 	if err := s.db.Table("attachments").
-		Select("attachments.kind, attachments.url, attachments.mime, attachments.size, attachments.width, attachments.height, attachments.created_at, users.nickname, users.username").
+		Select("attachments.kind, attachments.source, attachments.url, attachments.mime, attachments.size, attachments.width, attachments.height, attachments.created_at, users.nickname, users.username").
 		Joins("LEFT JOIN users ON users.id = attachments.user_id").
 		Scan(&rows).Error; err != nil {
 		return nil, nil, err
@@ -72,30 +94,22 @@ func (s *UploadService) AdminMediaLibrary() ([]MediaLibraryItem, map[string]int,
 	metaByURL := make(map[string]attMeta, len(rows))
 	// 远程存储对象（/api/media/）不在磁盘上，直接作为条目加入
 	items := make([]MediaLibraryItem, 0, len(rows))
-	categoryName := func(key string) string {
-		for _, cat := range mediaLibraryCategories {
-			if cat.Key == key {
-				return cat.Name
-			}
-		}
-		return key
-	}
 	for _, r := range rows {
 		metaByURL[r.URL] = r // 本地文件在磁盘扫描时按 URL 合并元数据
 		if !strings.HasPrefix(r.URL, "/api/media/") {
 			continue
 		}
+		if r.Kind != model.AttachmentKindImage && r.Kind != model.AttachmentKindAvatar {
+			continue // 未知 kind 不进媒体库
+		}
 		uploader := r.Nickname
 		if uploader == "" {
 			uploader = r.Username
 		}
-		cat := r.Kind
-		if cat != model.AttachmentKindImage && cat != model.AttachmentKindAvatar {
-			continue // 未知 kind 不进媒体库
-		}
+		catKey, catName := mediaCategoryForAttachment(r.Kind, r.Source)
 		ca := r.CreatedAt
 		items = append(items, MediaLibraryItem{
-			URL: r.URL, Category: cat, CategoryName: categoryName(cat),
+			URL: r.URL, Category: catKey, CategoryName: catName,
 			Name: strings.TrimPrefix(r.URL, "/api/media/"), MIME: r.MIME,
 			Size: int64(r.Size), Width: r.Width, Height: r.Height,
 			Uploader: uploader, UploadedAt: &ca,
@@ -153,6 +167,11 @@ func (s *UploadService) AdminMediaLibrary() ([]MediaLibraryItem, map[string]int,
 				if m.Width > 0 {
 					item.Width, item.Height = m.Width, m.Height
 				}
+				// 书库封面 / 正文插图改归“书籍”分类
+				if m.Source == model.AttachmentSourceLibraryCover || m.Source == model.AttachmentSourceLibraryContent {
+					item.Category = mediaCategoryBook
+					item.CategoryName = mediaCategoryBookName
+				}
 			}
 			// 无尺寸记录时读图片头解析宽高（失败不阻断，保持 0）
 			if item.Width == 0 && item.Size > 0 && item.Size <= 20<<20 {
@@ -243,6 +262,8 @@ func (s *UploadService) attachMediaSources(items []MediaLibraryItem) {
 	postByURL := map[string]postRef{}
 	type commentRef struct {
 		id, postID uint
+		floor      uint
+		isRoot     bool
 	}
 	commentByURL := map[string]commentRef{}
 
@@ -299,6 +320,19 @@ func (s *UploadService) attachMediaSources(items []MediaLibraryItem) {
 		}
 	}
 
+	// 评论锚点改用所属帖内相对楼层号（#comment-{floor}，楼中楼追加 -r{id}）
+	commentIDs := make([]uint, 0, len(commentByURL))
+	for _, cm := range commentByURL {
+		commentIDs = append(commentIDs, cm.id)
+	}
+	commentAnchors := CommentAnchors(s.db, commentIDs)
+	for u, cm := range commentByURL {
+		if a, ok := commentAnchors[cm.id]; ok {
+			cm.floor, cm.isRoot = a.Floor, a.IsRoot
+			commentByURL[u] = cm
+		}
+	}
+
 	// 评论来源要带宿主帖子标题，一次性补齐
 	postTitle := func(id uint) string {
 		var p model.Post
@@ -374,7 +408,15 @@ func (s *UploadService) attachMediaSources(items []MediaLibraryItem) {
 				break
 			}
 			if cm, ok := commentByURL[u]; ok {
-				it.SourceURL = fmt.Sprintf("/post/%d#comment-%d", cm.postID, cm.id)
+				if cm.floor > 0 {
+					if cm.isRoot {
+						it.SourceURL = fmt.Sprintf("/post/%d#comment-%d", cm.postID, cm.floor)
+					} else {
+						it.SourceURL = fmt.Sprintf("/post/%d#comment-%d-r%d", cm.postID, cm.floor, cm.id)
+					}
+				} else {
+					it.SourceURL = fmt.Sprintf("/post/%d", cm.postID)
+				}
 				title := commentPostTitle[cm.postID]
 				if title != "" {
 					it.SourceLabel = "帖子《" + truncate(title, 40) + "》下的评论"