feat(comments): 支持编辑与管理可见历史，采纳展示改用楼层号

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/handler/comment.go

@@ -106,6 +106,39 @@ func (h *Handlers) CreateComment(c *gin.Context) {
 	c.JSON(http.StatusOK, gin.H{"comment": comment})
 }
 
+// UpdateComment 编辑评论（作者或版主）
+func (h *Handlers) UpdateComment(c *gin.Context) {
+	claims := middleware.CurrentUser(c)
+	cid, err := strconv.ParseUint(c.Param("cid"), 10, 64)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "无效的评论 ID"})
+		return
+	}
+	var body struct {
+		Content string `json:"content"`
+	}
+	if err := c.ShouldBindJSON(&body); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+	node, err := h.Comment.Update(h.loadActor(claims.ID), uint(cid), claims.ID, body.Content)
+	if err != nil {
+		switch {
+		case errors.Is(err, service.ErrCommentNotFound):
+			c.JSON(http.StatusNotFound, gin.H{"error": err.Error()})
+		case errors.Is(err, service.ErrCommentForbidden):
+			c.JSON(http.StatusForbidden, gin.H{"error": err.Error()})
+		case errors.Is(err, service.ErrCommentDeleted),
+			errors.Is(err, service.ErrCommentNotChanged):
+			c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		default:
+			c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		}
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"comment": node})
+}
+
 // DeleteComment 软删评论（占位；自删与管理删均须填理由，管理删另须类型）
 func (h *Handlers) DeleteComment(c *gin.Context) {
 	claims := middleware.CurrentUser(c)