This commit introduces a `ResetModel()` function to `AgentViewModel` and `MineAgentViewModel` to clear their state.
This function is now called in `ResourceCleanupManager` and `AppState` during logout or when switching accounts to ensure that data from the previous session is not retained.
Additionally, the search and group name input fields in `CreateGroupChatScreen` are now single-line.
Refactors password validation logic to use a common `PasswordValidator` utility. This ensures consistent password validation rules across different parts of the application, including:
- User login
- Email sign-up
- Password change
- Account removal
Also adds a string resource for password too long error message.
