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/GroupSchema.ts

@@ -0,0 +1,20 @@
+export const GROUPS_TABLE = 'groups';
+export const GROUP_MEMBERS_TABLE = 'group_members';
+
+export const CREATE_GROUPS_TABLE = `CREATE TABLE IF NOT EXISTS groups (
+  id TEXT PRIMARY KEY NOT NULL,
+  data TEXT NOT NULL,
+  updatedAt TEXT NOT NULL
+)`;
+
+export const CREATE_GROUP_MEMBERS_TABLE = `CREATE TABLE IF NOT EXISTS group_members (
+  groupId TEXT NOT NULL,
+  userId TEXT NOT NULL,
+  data TEXT NOT NULL,
+  updatedAt TEXT NOT NULL,
+  PRIMARY KEY (groupId, userId)
+)`;
+
+export const CREATE_GROUP_INDEXES = [
+  `CREATE INDEX IF NOT EXISTS idx_group_members_groupId ON group_members(groupId)`,
+];