feat(chat): implement sequence pre-allocation, versioned sync, and push worker

Introduce several performance and synchronization enhancements:
- Implement `SeqBufferManager` to allow sequence number pre-allocation via Redis Lua scripts, reducing atomic increment overhead.
- Add `PushWorker` to handle asynchronous message pushing using Redis Streams.
- Implement incremental conversation synchronization via `ConversationVersionLog` to allow clients to fetch only recent changes.
- Add support for Gzip compression in WebSocket communications to reduce bandwidth usage.
- Update dependency injection and configuration to support these new components.

internal/dto/sync_dto.go

@@ -0,0 +1,23 @@
+package dto
+
+// SyncVersionRequest 增量同步请求
+type SyncVersionRequest struct {
+	Version int64 `form:"version" binding:"min=0"` // 客户端上次同步版本号，0 表示全量同步
+}
+
+// SyncVersionResponse 增量同步响应
+type SyncVersionResponse struct {
+	CurrentVersion int64            `json:"current_version"` // 服务端当前最大版本号
+	Changes        []SyncChangeItem `json:"changes"`         // 变更列表
+	FullSync       bool             `json:"full_sync"`       // 是否需要全量同步（版本差距过大时）
+	HasMore        bool             `json:"has_more"`        // 是否还有更多变更
+}
+
+// SyncChangeItem 单条变更项
+type SyncChangeItem struct {
+	ConversationID string `json:"conversation_id"`
+	ChangeType     string `json:"change_type"` // new_msg, read, pin, unpin, mute, unmute, hide, group_update
+	MaxSeq         int64  `json:"max_seq,omitempty"`
+	LastMessageAt  int64  `json:"last_message_at,omitempty"`
+	Version        int64  `json:"version"`
+}