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/database/schema/MigrationManager.ts

@@ -0,0 +1,57 @@
+import type { SQLiteDatabase } from 'expo-sqlite';
+import {
+  CREATE_MESSAGES_TABLE,
+  CREATE_MESSAGES_INDEXES,
+  MIGRATE_MESSAGES_TABLE,
+} from './MessageSchema';
+import {
+  CREATE_CONVERSATIONS_TABLE,
+  CREATE_CONVERSATION_CACHE_TABLE,
+  CREATE_CONVERSATION_LIST_CACHE_TABLE,
+  MIGRATE_CONVERSATIONS_TABLE,
+} from './ConversationSchema';
+import {
+  CREATE_USERS_TABLE,
+  CREATE_CURRENT_USER_CACHE_TABLE,
+} from './UserSchema';
+import {
+  CREATE_GROUPS_TABLE,
+  CREATE_GROUP_MEMBERS_TABLE,
+  CREATE_GROUP_INDEXES,
+} from './GroupSchema';
+import {
+  CREATE_POSTS_CACHE_TABLE,
+} from './PostSchema';
+
+export async function runMigrations(db: SQLiteDatabase): Promise<void> {
+  if (typeof window !== 'undefined') {
+    try {
+      await db.execAsync(`PRAGMA locking_mode = EXCLUSIVE;`);
+      await db.execAsync(`PRAGMA journal_mode = MEMORY;`);
+      await db.execAsync(`PRAGMA temp_store = MEMORY;`);
+      console.log('[MigrationManager] Web: 已设置 EXCLUSIVE locking + MEMORY journal/temp 模式');
+    } catch (e) {
+      console.warn('[MigrationManager] 设置 PRAGMA 失败:', e);
+    }
+  }
+
+  await db.execAsync(CREATE_MESSAGES_TABLE);
+  await db.execAsync(CREATE_CONVERSATIONS_TABLE);
+  await db.execAsync(CREATE_CONVERSATION_CACHE_TABLE);
+  await db.execAsync(CREATE_CONVERSATION_LIST_CACHE_TABLE);
+  await db.execAsync(CREATE_USERS_TABLE);
+  await db.execAsync(CREATE_CURRENT_USER_CACHE_TABLE);
+  await db.execAsync(CREATE_GROUPS_TABLE);
+  await db.execAsync(CREATE_GROUP_MEMBERS_TABLE);
+  await db.execAsync(CREATE_POSTS_CACHE_TABLE);
+
+  for (const indexSql of CREATE_MESSAGES_INDEXES) {
+    await db.execAsync(indexSql);
+  }
+  for (const indexSql of CREATE_GROUP_INDEXES) {
+    await db.execAsync(indexSql);
+  }
+
+  await MIGRATE_MESSAGES_TABLE(db);
+  await MIGRATE_CONVERSATIONS_TABLE(db);
+}