feat(api): add message segments support for posts and comments

Add rich message segment support enabling structured content (text, images, votes, mentions) in posts and comments. Includes segments field in models, DTOs, handlers, and services. Also adds @mention notification processing and migrates vote data to embedded segments.

internal/handler/comment_handler.go

@@ -1,4 +1,4 @@
-package handler
+package handler
 
 import (
 	"encoding/json"
@@ -7,6 +7,7 @@ import (
 	"github.com/gin-gonic/gin"
 
 	"with_you/internal/dto"
+	"with_you/internal/model"
 	"with_you/internal/pkg/cursor"
 	"with_you/internal/pkg/response"
 	"with_you/internal/service"
@@ -33,10 +34,11 @@ func (h *CommentHandler) Create(c *gin.Context) {
 	}
 
 	type CreateRequest struct {
-		PostID   string   `json:"post_id" binding:"required"`
-		Content  string   `json:"content"` // 内容可选，允许只发图片
-		ParentID *string  `json:"parent_id"`
-		Images   []string `json:"images"` // 图片URL列表
+		PostID   string                `json:"post_id" binding:"required"`
+		Content  string                `json:"content"`
+		Segments model.MessageSegments `json:"segments"`
+		ParentID *string               `json:"parent_id"`
+		Images   []string              `json:"images"`
 	}
 
 	var req CreateRequest
@@ -45,12 +47,18 @@ func (h *CommentHandler) Create(c *gin.Context) {
 		return
 	}
 
-	// 验证：评论必须有内容或图片
-	if req.Content == "" && len(req.Images) == 0 {
+	// 验证：评论必须有内容或图片或segments
+	if req.Content == "" && len(req.Images) == 0 && len(req.Segments) == 0 {
 		response.BadRequest(c, "评论内容或图片不能同时为空")
 		return
 	}
 
+	// 如果没有content但有segments，从segments提取文本
+	content := req.Content
+	if content == "" && len(req.Segments) > 0 {
+		content = dto.ExtractTextContent(req.Segments)
+	}
+
 	// 将图片列表转换为JSON字符串
 	var imagesJSON string
 	if len(req.Images) > 0 {
@@ -58,7 +66,7 @@ func (h *CommentHandler) Create(c *gin.Context) {
 		imagesJSON = string(imagesBytes)
 	}
 
-	comment, err := h.commentService.Create(c.Request.Context(), req.PostID, userID, req.Content, req.ParentID, imagesJSON, req.Images)
+	comment, err := h.commentService.Create(c.Request.Context(), req.PostID, userID, content, req.Segments, req.ParentID, imagesJSON, req.Images)
 	if err != nil {
 		response.InternalServerError(c, "failed to create comment")
 		return