Replace websocket flow with SSE support in backend.

Update handlers, services, router, and data conversion logic to support server-sent events and related message pipeline changes.

Made-with: Cursor

internal/dto/dto.go

@@ -68,6 +68,7 @@ type PostResponse struct {
 	Title          string              `json:"title"`
 	Content        string              `json:"content"`
 	Images         []PostImageResponse `json:"images"`
+	Status         string              `json:"status,omitempty"`
 	LikesCount     int                 `json:"likes_count"`
 	CommentsCount  int                 `json:"comments_count"`
 	FavoritesCount int                 `json:"favorites_count"`
@@ -77,6 +78,7 @@ type PostResponse struct {
 	IsLocked       bool                `json:"is_locked"`
 	IsVote         bool                `json:"is_vote"`
 	CreatedAt      string              `json:"created_at"`
+	UpdatedAt      string              `json:"updated_at"`
 	Author         *UserResponse       `json:"author"`
 	IsLiked        bool                `json:"is_liked"`
 	IsFavorited    bool                `json:"is_favorited"`