refactor(stores): reorganize flat store files into modular directory structure

Migrate from flat file organization to modular directory structure under src/stores/:

- auth/: authStore, registerStore, verificationStore, sessionStore
- call/: callStore
- settings/: chatSettingsStore, themeStore
- ui/: homeTabBarVisibilityStore, homeTabPressStore
- utils/: routePayloadCache
- group/sources.ts, group/profileResolver.ts
- message/sources.ts
- post/sources.ts

Update all import paths across components and screens to use new module paths. Maintain backward compatibility through deprecated re-export files for gradual migration.

src/screens/message/components/ChatScreen/GroupInfoPanel.tsx

@@ -20,7 +20,7 @@ import { Avatar, Text } from '../../../../components/common';
 import { useAppColors, spacing, fontSizes, shadows, type AppColors } from '../../../../theme';
 import { GroupMemberResponse, GroupResponse, GroupAnnouncementResponse } from '../../../../types/dto';
 import { useBreakpointGTE } from '../../../../hooks/useResponsive';
-import { groupManager } from '../../../../stores/groupManager';
+import { groupManager } from '../../../../stores/group';
 import { groupService } from '@/services/message';
 
 const { width: screenWidth } = Dimensions.get('window');

src/screens/message/components/ChatScreen/GroupInfoPanel.web.tsx

@@ -20,7 +20,7 @@ import { Avatar, Text } from '../../../../components/common';
 import { useAppColors, spacing, fontSizes, shadows, borderRadius, type AppColors } from '../../../../theme';
 import { GroupMemberResponse, GroupResponse, GroupAnnouncementResponse } from '../../../../types/dto';
 import { useBreakpointGTE } from '../../../../hooks/useResponsive';
-import { groupManager } from '../../../../stores/groupManager';
+import { groupManager } from '../../../../stores/group';
 import { groupService } from '@/services/message';
 
 const { width: screenWidth } = Dimensions.get('window');

src/screens/message/components/ChatScreen/SegmentRenderer.tsx

@@ -33,7 +33,7 @@ import {
 } from '../../../../types/dto';
 import { spacing, useAppColors, type AppColors } from '../../../../theme';
 import { SenderInfo } from './types';
-import { useChatSettingsStore } from '../../../../stores/chatSettingsStore';
+import { useChatSettingsStore } from '../../../../stores/settings';
 
 const IMAGE_MAX_WIDTH = 200;
 const IMAGE_MAX_HEIGHT = 260;

src/screens/message/components/ChatScreen/bubbleStyles.ts

@@ -5,7 +5,7 @@
 
 import { StyleSheet, ViewStyle, TextStyle } from 'react-native';
 import { spacing, type AppColors } from '../../../../theme';
-import { useChatSettingsStore } from '../../../../stores/chatSettingsStore';
+import { useChatSettingsStore } from '../../../../stores/settings';
 
 // 默认圆角，但会从 store 读取
 export const BUBBLE_RADIUS = 16;

src/screens/message/components/ChatScreen/styles.ts

@@ -6,7 +6,7 @@
 import { useMemo } from 'react';
 import { StyleSheet, Dimensions } from 'react-native';
 import { spacing, shadows, useAppColors, type AppColors } from '../../../../theme';
-import { useChatSettingsStore, CHAT_THEMES } from '../../../../stores/chatSettingsStore';
+import { useChatSettingsStore, CHAT_THEMES } from '../../../../stores/settings';
 
 const { width: SCREEN_WIDTH } = Dimensions.get('window');
 

src/screens/message/components/ChatScreen/useChatScreen.ts

@@ -28,8 +28,8 @@ import { ApiError } from '@/services/core';
 // 【新架构】使用 MessageManager
 import { useChat, useGroupTyping, useGroupMuted, messageManager, callStore } from '../../../../stores';
 import { groupService } from '@/services/message';
-import { userManager } from '../../../../stores/userManager';
-import { groupManager } from '../../../../stores/groupManager';
+import { userManager } from '../../../../stores/user';
+import { groupManager } from '../../../../stores/group';
 import * as hrefs from '../../../../navigation/hrefs';
 import { firstRouteParam } from '../../../../navigation/paramUtils';
 import {