refactor(database): migrate to new modular database layer and unify data access

- Remove legacy database.ts, LocalDataSource.ts, and MessageRepository.ts
- Create new src/database/ module with messageRepository, userCacheRepository, conversationRepository, and groupCacheRepository
- Update all consumers to import from @/database instead of services/database
- Add web platform blur handling for modal components to fix focus issues
- Flatten SystemMessageItem and NotificationsScreen styles for consistent design
- Add draggable slider in ChatSettingsScreen and dynamic font size support
- Introduce 9 new chat color themes
- Add profile screens for about, terms, and privacy policy with navigation routes
- Add policy links to login and registration screens
- Fix post share URL format from /posts/ to /post/

src/components/common/AdaptiveLayout.tsx

@@ -15,6 +15,7 @@ import {
   Modal,
   Pressable,
   Dimensions,
+  Platform,
 } from 'react-native';
 import {
   useResponsive,
@@ -159,6 +160,10 @@ export function AdaptiveLayout({
   // 抽屉动画
   useEffect(() => {
     if (isDrawerOpen) {
+      if (Platform.OS === 'web') {
+        const active = (globalThis as any)?.document?.activeElement as { blur?: () => void } | undefined;
+        active?.blur?.();
+      }
       Animated.parallel([
         Animated.timing(slideAnim, {
           toValue: 1,

src/components/common/AppDialogHost.tsx

@@ -1,5 +1,5 @@
 import React, { useEffect, useMemo, useState } from 'react';
-import { Modal, Pressable, StyleSheet, Text, TouchableOpacity, View } from 'react-native';
+import { Modal, Pressable, StyleSheet, Text, TouchableOpacity, View, Platform } from 'react-native';
 import type { AlertButton } from 'react-native';
 import { MaterialCommunityIcons } from '@expo/vector-icons';
 import { LinearGradient } from 'expo-linear-gradient';
@@ -93,6 +93,12 @@ function createDialogHostStyles(colors: AppColors) {
   });
 }
 
+const blurActiveElementOnWeb = () => {
+  if (Platform.OS !== 'web') return;
+  const active = (globalThis as any)?.document?.activeElement as { blur?: () => void } | undefined;
+  active?.blur?.();
+};
+
 const AppDialogHost: React.FC = () => {
   const [dialog, setDialog] = useState<DialogPayload | null>(null);
   const colors = useAppColors();
@@ -105,6 +111,12 @@ const AppDialogHost: React.FC = () => {
     return unbind;
   }, []);
 
+  useEffect(() => {
+    if (dialog) {
+      blurActiveElementOnWeb();
+    }
+  }, [dialog]);
+
   const actions = useMemo<AlertButton[]>(() => {
     if (!dialog?.actions?.length) return [{ text: '确定' }];
     return dialog.actions;

src/components/common/ImageGallery.tsx

@@ -14,6 +14,7 @@ import {
   Text,
   StatusBar,
   Alert,
+  Platform,
 } from 'react-native';
 import { Image as ExpoImage } from 'expo-image';
 import {
@@ -126,6 +127,10 @@ export const ImageGallery: React.FC<ImageGalleryProps> = ({
   // 打开/关闭时重置状态
   useEffect(() => {
     if (visible) {
+      if (Platform.OS === 'web') {
+        const active = (globalThis as any)?.document?.activeElement as { blur?: () => void } | undefined;
+        active?.blur?.();
+      }
       setCurrentIndex(initialIndex);
       setShowControls(true);
       setError(false);

src/components/common/VideoPlayerModal.tsx

@@ -3,7 +3,7 @@
  * 全屏模态播放视频，基于 expo-video
  */
 
-import React, { useCallback } from 'react';
+import React, { useCallback, useEffect } from 'react';
 import {
   Modal,
   View,
@@ -12,6 +12,7 @@ import {
   TouchableOpacity,
   Text,
   StatusBar,
+  Platform,
 } from 'react-native';
 import { VideoView, useVideoPlayer } from 'expo-video';
 import { MaterialCommunityIcons } from '@expo/vector-icons';
@@ -79,6 +80,13 @@ export const VideoPlayerModal: React.FC<VideoPlayerModalProps> = ({
   url,
   onClose,
 }) => {
+  useEffect(() => {
+    if (visible && Platform.OS === 'web') {
+      const active = (globalThis as any)?.document?.activeElement as { blur?: () => void } | undefined;
+      active?.blur?.();
+    }
+  }, [visible]);
+
   return (
     <Modal
       visible={visible}