fix: remove unimplemented notification page

[rileychh]

Description

This PR removes the unimplemented notification page from the project. This includes cleaning up associated localization strings, dependencies, and unused code. The notification page was previously a placeholder and is no longer planned for implementation.

Implementation

• Removed NotificationPage widget and its related file (lib/ui/pages/notification/notification_page.dart).
• Updated MainScreen to exclude the notification page from the navigation structure.
• Deleted the titleNotification localization strings from all relevant localization files (intl_en.dart, intl_zh_TW.dart, intl_en.arb, intl_zh_TW.arb).
• Cleaned up references to titleNotification in the generated localization classes (S).
• Verified the removal of references in the codebase to avoid broken dependencies.

Breaking Changes

• Removed a navigation tab for the notification page, which may affect users if the page was accessible via routes or other manual integrations.

Testing Instructions

1. Code Review

   • Confirm that all references to NotificationPage and titleNotification have been successfully removed.
   • Verify that there are no remaining imports or calls to the deleted files/classes.

2. Manual Testing

   • Build and run the app.
   • Verify that the notification tab no longer appears in the bottom navigation bar.
   • Ensure all other tabs and functionality remain unaffected.

Additional Notes

• The notification page may be reintroduced in the future if required. The removed implementation is available in the commit history for reference.