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/config/push_worker.go

@@ -0,0 +1,13 @@
+package config
+
+// PushWorkerConfig 推送 Worker 配置（Redis Stream 异步推送）
+type PushWorkerConfig struct {
+	Enabled       bool  `mapstructure:"enabled"`
+	Stream        string `mapstructure:"stream"`          // Redis Stream 名称，默认 "msg_push"
+	Group         string `mapstructure:"group"`           // Consumer Group 名称，默认 "push_worker"
+	BatchSize     int   `mapstructure:"batch_size"`      // XREADGROUP 每次读取条数，默认 50
+	PollTimeoutMs int   `mapstructure:"poll_timeout_ms"` // XREADGROUP BLOCK 超时 ms，默认 2000
+	MaxRetries    int   `mapstructure:"max_retries"`     // 消息最大重试次数，默认 3
+	MaxStreamLen  int64 `mapstructure:"max_stream_len"`  // Stream MAXLEN，默认 100000
+	IdleTimeoutMs int64 `mapstructure:"idle_timeout_ms"` // XPENDING 空闲超时 ms，默认 30000
+}