[Enhancement]: Add Tests for `NotificationScreen` and `NotificationViewModel`

[theMr17]

Summary of Improvement

Add UI and unit tests for the NotificationScreen and NotificationViewModel introduced by #22.

Current Implementation

Currently, there are no tests covering the NotificationScreen composable or the associated NotificationViewModel. This makes it difficult to ensure UI correctness, especially during refactors or feature additions.

Proposed Solution

• Create a test class for NotificationViewModel that verifies:

  • Initial UI state
  • Notification loading behavior
  • Read/unread status updates
  • Edge cases like empty or failed notification lists

• Create an instrumented test for NotificationScreen that verifies:

  • UI renders correctly with sample data
  • Click events navigate or respond appropriately
  • Unread badge visibility logic works as expected

The structure and strategy should follow existing patterns in:

• SetupViewModelTest
• LoginViewModelTest
• SetupScreenTest
• LoginScreenTest