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');