PAINTROID-753 Write Integration tests for WorkspacePage menu

[Amit-Matth]

This PR introduces integration tests covering core navigation and overflow menu actions in WorkspacePage, ensuring reliable user interactions during back navigation, fullscreen mode, and canvas management.

PAINTROID-753

New Features and Enhancements

• Added integration tests for WorkspacePage features:
  • Overflow menu options visibility
  • "New Image" workflow with discard/save handling
  • Fullscreen toggle with back navigation
  • Unsaved changes discard dialog behavior

Refactorings and Bug Fixes

• Added two new localization strings:
• "Save" – for confirming saving work
• "Discard" – for confirming discarding changes

Checklist

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