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/seq_buffer.go

@@ -0,0 +1,10 @@
+package config
+
+// SeqBufferConfig seq 预分配配置
+type SeqBufferConfig struct {
+	Enabled           bool `mapstructure:"enabled"`
+	PrivateBufferSize int  `mapstructure:"private_buffer_size"` // 私聊预分配步长（默认 50）
+	GroupBufferSize   int  `mapstructure:"group_buffer_size"`   // 群聊预分配步长（默认 200）
+	LockTimeoutMs     int  `mapstructure:"lock_timeout_ms"`     // 分布式锁超时毫秒（默认 5000）
+	MaxRetries        int  `mapstructure:"max_retries"`         // 冷启动重试次数（默认 3）
+}