feat: 添加内容置顶功能，更新相关数据模型和前端视图

backend/app/http/v1/dto/upload.go

@@ -9,9 +9,9 @@ type UploadInitForm struct {
 }
 
 type UploadInitResponse struct {
-	UploadID string `json:"upload_id"`
-	Key      string `json:"key"` // For S3 direct
-	ChunkSize int64 `json:"chunk_size"`
+	UploadID  string `json:"upload_id"`
+	Key       string `json:"key"` // For S3 direct
+	ChunkSize int64  `json:"chunk_size"`
 }
 
 type UploadPartForm struct {