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/admin_content.go

@@ -49,11 +49,11 @@ const (
 
 // AdminContentCounts 当前操作者可见范围内的数量（用于页内 Tab）
 type AdminContentCounts struct {
-	PostsLive      int64 `json:"posts_live"`
-	PostsPending   int64 `json:"posts_pending"`
-	PostsRejected  int64 `json:"posts_rejected"`
-	PostsDeleted   int64 `json:"posts_deleted"`
-	CommentsLive   int64 `json:"comments_live"`
+	PostsLive        int64 `json:"posts_live"`
+	PostsPending     int64 `json:"posts_pending"`
+	PostsRejected    int64 `json:"posts_rejected"`
+	PostsDeleted     int64 `json:"posts_deleted"`
+	CommentsLive     int64 `json:"comments_live"`
 	CommentsPending  int64 `json:"comments_pending"`
 	CommentsRejected int64 `json:"comments_rejected"`
 	CommentsDeleted  int64 `json:"comments_deleted"`
@@ -61,32 +61,34 @@ type AdminContentCounts struct {
 
 // AdminContentPost 后台帖子列表项
 type AdminContentPost struct {
-	ID           uint       `json:"id"`
-	Title        string     `json:"title"`
-	Status       string     `json:"status"`
-	Deleted      bool       `json:"deleted"`
-	DeletedAt    *time.Time `json:"deleted_at,omitempty"`
-	CreatedAt    time.Time  `json:"created_at"`
-	CommentCount int        `json:"comment_count"`
-	BoardID      uint       `json:"board_id"`
+	ID           uint        `json:"id"`
+	Title        string      `json:"title"`
+	Status       string      `json:"status"`
+	Deleted      bool        `json:"deleted"`
+	DeletedAt    *time.Time  `json:"deleted_at,omitempty"`
+	CreatedAt    time.Time   `json:"created_at"`
+	CommentCount int         `json:"comment_count"`
+	BoardID      uint        `json:"board_id"`
 	Board        model.Board `json:"board"`
-	User         model.User `json:"user"`
+	User         model.User  `json:"user"`
 }
 
 // AdminContentComment 后台评论列表项
 type AdminContentComment struct {
-	ID        uint       `json:"id"`
-	PostID    uint       `json:"post_id"`
-	PostTitle string     `json:"post_title"`
-	BoardID   uint       `json:"board_id"`
-	Content   string     `json:"content"`
-	Status    string     `json:"status"`
-	Edited    bool       `json:"edited"` // 相对创建已编辑（同评论侧规则），用于隐藏无修订的历史入口
-	Deleted   bool       `json:"deleted"`
-	DeletedAt *time.Time `json:"deleted_at,omitempty"`
-	CreatedAt time.Time  `json:"created_at"`
+	ID        uint        `json:"id"`
+	PostID    uint        `json:"post_id"`
+	PostTitle string      `json:"post_title"`
+	BoardID   uint        `json:"board_id"`
+	Content   string      `json:"content"`
+	Status    string      `json:"status"`
+	Edited    bool        `json:"edited"` // 相对创建已编辑（同评论侧规则），用于隐藏无修订的历史入口
+	Deleted   bool        `json:"deleted"`
+	DeletedAt *time.Time  `json:"deleted_at,omitempty"`
+	CreatedAt time.Time   `json:"created_at"`
+	Floor     uint        `json:"floor"`   // 所属楼层相对序号
+	IsRoot    bool        `json:"is_root"` // 主楼/楼中楼，供前台拼 #comment-{floor}[-r{id}]
 	Board     model.Board `json:"board"`
-	User      model.User `json:"user"`
+	User      model.User  `json:"user"`
 }
 
 func normalizeAdminStatus(raw string) AdminContentStatus {
@@ -270,6 +272,11 @@ func (s *ModerationService) ListAdminComments(actor *Actor, status, keyword stri
 	}
 
 	items := make([]AdminContentComment, 0, len(rows))
+	commentIDs := make([]uint, 0, len(rows))
+	for _, r := range rows {
+		commentIDs = append(commentIDs, r.ID)
+	}
+	anchors := CommentAnchors(s.db, commentIDs)
 	for _, r := range rows {
 		it := AdminContentComment{
 			ID:        r.ID,
@@ -283,6 +290,10 @@ func (s *ModerationService) ListAdminComments(actor *Actor, status, keyword stri
 			Board:     boards[r.BoardID],
 			User:      users[r.UserID],
 		}
+		if a, ok := anchors[r.ID]; ok {
+			it.Floor = a.Floor
+			it.IsRoot = a.IsRoot
+		}
 		if r.DeletedAt.Valid {
 			it.Deleted = true
 			t := r.DeletedAt.Time