refactor: improve system stability, performance, and code structure

This commit introduces several architectural improvements and optimizations across the codebase:

- **Performance & Reliability**:
  - Implemented Redis pipelining in `ConversationCache.CacheMessage` to reduce network round-trips.
  - Added a circuit breaker to the JPush client to prevent cascading failures.
  - Introduced batch deletion and batch member addition capabilities in repositories.
  - Added message idempotency support using `client_msg_id` and a Redis-based cache.
  - Optimized WebSocket handling with connection limits (total and per-user) and improved error logging.

- **Code Refactoring**:
  - Refactored `Router` to use a `RouterDeps` struct, simplifying the constructor and improving maintainability.
  - Unified model ID generation logic using new `id_helper.go` (supporting UUID and Snowflake).
  - Standardized JSON serialization/deserialization in models using `json_helper.go`.
  - Refactored DTO conversion logic, specifically for `UserResponse` (using functional options) and `Report` responses.
  - Removed redundant/deprecated DTOs like `PostDetailResponse` and `TradeItemDetailResponse`.

- **Cache Improvements**:
  - Enhanced `LayeredCache` with `SetRaw` to avoid double-encoding when promoting values from Redis to local cache.
  - Added `DeleteBatch` support to the cache interface.

- **Other Changes**:
  - Cleaned up `config.go` by removing redundant default values and explicit environment variable overrides.
  - Improved WebSocket registration flow to handle connection limits gracefully.

internal/dto/post_converter.go

@@ -124,50 +124,7 @@ func ConvertPostToResponse(post *model.Post, channelByID map[string]*model.Chann
 	}
 }
 
-// ConvertPostToDetailResponse 将Post转换为PostDetailResponse；channelByID 可为 nil
-func ConvertPostToDetailResponse(post *model.Post, channelByID map[string]*model.Channel, isLiked, isFavorited bool) *PostDetailResponse {
-	if post == nil {
-		return nil
-	}
-
-	images := make([]PostImageResponse, 0)
-	for _, img := range post.Images {
-		images = append(images, ConvertPostImageToResponse(&img))
-	}
-
-	var author *UserResponse
-	if post.User != nil {
-		author = ConvertUserToResponse(post.User)
-	}
-
-	return &PostDetailResponse{
-		ID:              post.ID,
-		UserID:          post.UserID,
-		ChannelID:       post.ChannelID,
-		Title:           post.Title,
-		Content:         post.Content,
-		Segments:        SegmentsOrDefault(post.Segments, post.Content),
-		Images:          images,
-		Status:          string(post.Status),
-		LikesCount:      post.LikesCount,
-		CommentsCount:   post.CommentsCount,
-		FavoritesCount:  post.FavoritesCount,
-		SharesCount:     post.SharesCount,
-		ViewsCount:      post.ViewsCount,
-		IsPinned:        post.IsPinned,
-		IsLocked:        post.IsLocked,
-		IsVote:          post.IsVote,
-		CreatedAt:       FormatTime(post.CreatedAt),
-		UpdatedAt:       FormatTime(post.UpdatedAt),
-		ContentEditedAt: FormatTimePointer(post.ContentEditedAt),
-		Author:          author,
-		IsLiked:         isLiked,
-		IsFavorited:     isFavorited,
-		Channel:         postChannelBrief(post, channelByID),
-	}
-}
-
-// ConvertPostsToResponse 将Post列表转换为响应列表（每个帖子独立检查点赞/收藏状态）；channelByID 可为 nil
+// ConvertPostsToResponse 将Post列表转换为响应列表；channelByID 可为 nil
 func ConvertPostsToResponse(posts []*model.Post, channelByID map[string]*model.Channel, isLikedMap, isFavoritedMap map[string]bool) []*PostResponse {
 	result := make([]*PostResponse, 0, len(posts))
 	for _, post := range posts {