Fix: localize text editor title

[Aryan-Singla]

For Issue:
Fixes #348

Description:

Context:
While working on the application, I identified that the TextFitEditor screen was using a hardcoded string ('Text Editor') for its AppBar title. This prevents the screen from being properly localized into other languages supported by the app.

Changes Made:

• Localization: Defined the textEditorTitle key in lib/l10n/app_en.arb to manage the UI string centrally.
• Code Refactoring: Updated lib/view/text_fit_editor.dart to fetch the AppBar title dynamically via AppLocalizations.of(context)!.textEditorTitle, removing the hardcoded value.
• Unit/Widget Testing:
  • Created a new test file: test/text_editor_localization_test.dart.
  • Implemented a widget test to verify that the AppBar title is correctly rendered from the localization system.
  • Configured the test environment to handle GetIt service locator and ColorPaletteProvider dependencies.

Impact:

• i18n Support: The app's header in the Text Editor section is now fully translatable.
• Reliability: The added widget test ensures that future changes won't break the localization or the UI initialization for this screen

Testing Verification:
Successfully verified the fix by running: flutter test test/text_editor_localization_test.dart

Result:
All tests passed!

Evidence:

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