fix: 实现空间 TotalReads 统计，修复 selectMention 闭包

- P0-2: posts/show.html selectMention 闭包 var→let 修复
- P0-3: GetUserStats 增加 SUM(views_count) 统计，替换硬编码 int64(0)
- 更新 Fix_List.md 标注 P0-1/2/3 已修复

internal/controller/space_controller.go

@@ -81,7 +81,7 @@ func (ctrl *SpaceController) ShowSpace(c *gin.Context) {
 
 	// 构建基础数据（含用户统计）
 	postCount, _ := ctrl.spaceService.CountUserPosts(uint(uid))
-	totalLikes, totalFavorites, _ := ctrl.spaceService.GetUserStats(uint(uid))
+	totalLikes, totalFavorites, totalReads, _ := ctrl.spaceService.GetUserStats(uint(uid))
 
 	data := gin.H{
 		"Title":         spaceUser.Username + " 的空间",
@@ -93,7 +93,7 @@ func (ctrl *SpaceController) ShowSpace(c *gin.Context) {
 		"PostCount":     postCount,
 		"TotalLikes":    totalLikes,
 		"TotalFavorites": totalFavorites,
-		"TotalReads":    int64(0), // 暂无阅读量统计
+		"TotalReads":    totalReads,
 	}
 
 	// ---- 根据 Tab 加载对应数据 ----