refactor(message): modularize MessageManager architecture

重构消息管理模块，将单体 MessageManager 拆分为职责单一的子模块：

- MessageStateManager: 纯状态管理
- MessageDeduplication: 消息去重服务
- UserCacheService: 用户缓存服务
- ReadReceiptManager: 已读回执管理
- ConversationOperations: 会话操作
- MessageSendService: 消息发送
- MessageSyncService: 消息同步
- WSMessageHandler: WebSocket 消息处理

新增类型定义和常量文件，保持原有 API 向后兼容。修复 CallScreen 状态值错误，补充 PostDetailScreen 缺失样式，优化 GroupInfoPanel 导入。

src/stores/message/index.ts

@@ -1,19 +1,66 @@
 /**
  * 消息模块统一导出
+ * 
+ * 提供向后兼容的 API 导出
  */
 
-// 导出主要的管理器
+// ==================== 主管理器 ====================
 export { messageManager, MessageManager } from './MessageManager';
 
-// 导出状态管理器
-export { messageStateManager, MessageStateManager } from './MessageStateManager';
-export type { MessageState, MessageEvent, MessageSubscriber, MessageEventType } from './MessageStateManager';
+// ==================== 类型导出 ====================
+// 从 types.ts 导出所有类型
+export type {
+  MessageEventType,
+  MessageEvent,
+  MessageSubscriber,
+  MessageManagerState,
+  ReadStateRecord,
+  MessageManagerConversationListDeps,
+  HandleNewMessageOptions,
+  IMessageStateManager,
+  IMessageDeduplication,
+  IUserCacheService,
+  IReadReceiptManager,
+  IConversationOperations,
+  IMessageSendService,
+  IMessageSyncService,
+  IWSMessageHandler,
+} from './types';
 
-// 导出同步服务
-export { messageSyncService, MessageSyncService } from './MessageSyncService';
+// ==================== 常量导出 ====================
+export {
+  READ_STATE_PROTECTION_DELAY,
+  PROCESSED_MESSAGE_ID_EXPIRY,
+  PROCESSED_MESSAGE_ID_MAX_SIZE,
+  MAX_FLUSH_ITERATIONS,
+  CONVERSATION_REFRESH_THROTTLE,
+  MIN_RECONNECT_SYNC_INTERVAL,
+} from './constants';
 
-// 导出WS处理器
-export { wsMessageHandler, WSMessageHandler } from './WSMessageHandler';
+// ==================== 子模块导出（可选使用）====================
+// 状态管理器
+export { MessageStateManager, messageStateManager } from './MessageStateManager';
 
-// 导出已读管理器
-export { readReceiptManager, ReadReceiptManager } from './ReadReceiptManager';
+// 消息去重服务
+export { MessageDeduplication, messageDeduplication } from './MessageDeduplication';
+
+// 用户缓存服务
+export { UserCacheService, userCacheService } from './UserCacheService';
+
+// 已读回执管理器
+export { ReadReceiptManager } from './ReadReceiptManager';
+
+// 会话操作服务
+export { ConversationOperations } from './ConversationOperations';
+
+// 消息发送服务
+export { MessageSendService } from './MessageSendService';
+
+// 消息同步服务
+export { MessageSyncService } from './MessageSyncService';
+
+// WebSocket 消息处理器
+export { WSMessageHandler } from './WSMessageHandler';
+
+// ==================== 默认导出 ====================
+export { default } from './MessageManager';