feat: 实现赞/踩系统（P2）

- 新增 PostLike/PostDislike 模型，复合主键 (user_id, post_id)
- Post 表新增 LikesCount/DislikesCount 冗余计数器
- Repository 层：reaction_repo.go，含 WithTx 事务支持
- Service 层：reaction_service.go，赞踩互斥逻辑（6 态切换），事务包裹
- Controller 层：reaction_controller.go，3 个 API（ToggleLike/ToggleDislike/GetReaction）
- 接口定义：controller/interfaces.go 新增 reactionUseCase，service/repository.go 新增 ReactionStore
- 路由注册 + 依赖注入 + AutoMigrate
- 前端：文章详情页赞踩按钮 + 状态查询 + 401 跳转登录
- 样式：posts.css 新增赞踩按钮样式

internal/router/api.go

@@ -118,4 +118,17 @@ func setupAPIRoutes(r *gin.Engine, cfg *config.Config, d *dependencies) {
 		commentsAPI.GET("/users/search", d.commentCtrl.SearchUsers)
 		commentsAPI.POST("/comments/upload-image", d.commentCtrl.UploadImage)
 	}
+
+	// --- 赞/踩 API ---
+	// 公开：查询反应状态（未登录返回 none + 点赞数）
+	r.GET("/api/posts/:id/reaction", d.reactionCtrl.GetReaction)
+	// 需登录：切换赞/踩
+	reactionAPI := r.Group("/api/posts/:id")
+	reactionAPI.Use(d.authMdw.Required())
+	reactionAPI.Use(d.authMdw.BannedWriteGuard())
+	reactionAPI.Use(middleware.CSRF(cfg))
+	{
+		reactionAPI.POST("/like", d.reactionCtrl.ToggleLike)
+		reactionAPI.POST("/dislike", d.reactionCtrl.ToggleDislike)
+	}
 }

internal/router/deps_core.go

@@ -37,6 +37,7 @@ type dependencies struct {
 	commentCtrl     *controller.CommentController
 	commentService  *service.CommentService
 	adminCommentCtrl *adminCtrl.AdminCommentController
+	reactionCtrl    *controller.ReactionController
 }
 
 func buildDepsCore(db *gorm.DB, cfg *config.Config, siteSettings *config.SiteSettings, redisClient *redis.Client) (

internal/router/deps_extra.go

@@ -69,6 +69,11 @@ func buildDeps(db *gorm.DB, cfg *config.Config, siteSettings *config.SiteSetting
 	// 后台评论管理
 	adminCommentCtrl := adminCtrl.NewAdminCommentController(commentService)
 
+	// 赞/踩系统
+	reactionRepo := repository.NewReactionRepo(db)
+	reactionService := service.NewReactionService(db, reactionRepo)
+	reactionCtrl := controller.NewReactionController(reactionService)
+
 	// 用户空间
 	spaceService := service.NewSpaceService(userRepo, postRepo)
 	spaceCtrl := controller.NewSpaceController(spaceService)
@@ -90,5 +95,6 @@ func buildDeps(db *gorm.DB, cfg *config.Config, siteSettings *config.SiteSetting
 		commentCtrl:     commentCtrl,
 		commentService:  commentService,
 		adminCommentCtrl: adminCommentCtrl,
+		reactionCtrl:    reactionCtrl,
 	}
 }