refactor: 架构重构 - 解耦过度耦合模块

主要改动:
1. 创建乐观更新工具函数 (optimisticUpdate.ts)
   - 消除 userStore.ts 中的重复代码

2. 拆分 useResponsive.ts (485行 -> 12个专注模块)
   - useBreakpoint: 断点检测
   - useOrientation: 方向检测
   - usePlatform: 平台检测
   - useScreenSize: 屏幕尺寸
   - useResponsiveValue: 响应式值
   - useResponsiveStyle: 响应式样式
   - useMediaQuery: 媒体查询
   - useColumnCount: 列数计算
   - useResponsiveSpacing: 响应式间距

3. 整理数据层 (Repository 层)
   - ApiDataSource: API数据源
   - LocalDataSource: 本地数据源
   - CacheDataSource: 缓存数据源
   - MessageRepository: 消息仓库

4. 重构 messageManager.ts (2194行 -> 4个模块)
   - MessageStateManager: 状态管理
   - WebSocketMessageHandler: WebSocket处理
   - MessageSyncService: 消息同步
   - ReadReceiptManager: 已读管理

5. 导航解耦 (MainNavigator.tsx: 1118行 -> 100行)
   - 创建 NavigationService 解耦层
   - 拆分多个 Navigator 组件

架构改进:
- 单一职责原则: 每个模块职责明确
- 依赖倒置: 通过接口解耦
- 代码复用: 工具函数可被多处使用
- 可测试性: 各模块可独立测试

src/presentation/hooks/responsive/useScreenSize.ts

@@ -0,0 +1,63 @@
+/**
+ * useScreenSize Hook
+ * 屏幕尺寸检测 - 提供屏幕尺寸和断点信息
+ */
+
+import { useState, useEffect, useMemo } from 'react';
+import { Dimensions, ScaledSize } from 'react-native';
+import { getBreakpoint, getFineBreakpoint } from './useBreakpoint';
+import type { BreakpointKey, FineBreakpointKey, ScreenSize } from './types';
+
+/**
+ * 获取窗口尺寸，支持屏幕旋转响应
+ * 替代 Dimensions.get('window')，提供实时尺寸更新
+ */
+export function useWindowDimensions(): ScaledSize {
+  const [dimensions, setDimensions] = useState(() => Dimensions.get('window'));
+
+  useEffect(() => {
+    const subscription = Dimensions.addEventListener('change', ({ window }) => {
+      setDimensions(window);
+    });
+
+    return () => {
+      subscription.remove();
+    };
+  }, []);
+
+  return dimensions;
+}
+
+/**
+ * 屏幕尺寸 Hook
+ * 提供屏幕尺寸信息和断点状态
+ * 
+ * @returns 屏幕尺寸信息
+ * 
+ * @example
+ * const { width, height, isMobile, isTablet, isDesktop, isWide } = useScreenSize();
+ */
+export function useScreenSize(): ScreenSize & {
+  breakpoint: BreakpointKey;
+  fineBreakpoint: FineBreakpointKey;
+} {
+  const { width, height } = useWindowDimensions();
+
+  return useMemo(() => {
+    const breakpoint = getBreakpoint(width);
+    const fineBreakpoint = getFineBreakpoint(width);
+
+    return {
+      width,
+      height,
+      breakpoint,
+      fineBreakpoint,
+      isMobile: breakpoint === 'mobile',
+      isTablet: breakpoint === 'tablet',
+      isDesktop: breakpoint === 'desktop',
+      isWide: breakpoint === 'wide',
+    };
+  }, [width, height]);
+}
+
+export default useScreenSize;