Enhance localization and improve device questionnaire handling

[Andx667]

Description

This pull request introduces improvements to localization handling, device questionnaire robustness, and test coverage. The most significant changes include ensuring all locales have complete key coverage with English as a fallback, improving the handling of missing devices in the questionnaire screen, and adding comprehensive tests for localization and device risk scoring logic.

Localization improvements:

• Ensured all supported locales have a complete set of localization keys by merging each locale's keys with English defaults, and provided a method to retrieve the set of keys for each locale. (lib/l10n/app_localizations.dart) [1] [2] [3]
• Added a test that verifies all supported locales have exactly the same keys as English, improving localization consistency. (test/app_localizations_test.dart)

Device questionnaire robustness:

• Improved device lookup in the questionnaire screen to handle missing devices gracefully by displaying a loading indicator and navigating back if the device is not found, preventing crashes. (lib/screens/device_questionnaire_screen.dart) [1] [2]
• Updated callbacks to pass the device instance explicitly, ensuring correct state updates and navigation. (lib/screens/device_questionnaire_screen.dart) [1] [2]

Test coverage enhancements:

• Added tests to verify that all non-generic device questions have dedicated remedies and that "don't know" answers only trigger the generic learning action, improving the reliability of device risk scoring logic. (test/device_risk_scoring_test.dart)

Other changes:

• Updated the app version to 1.0.0+5. (pubspec.yaml)
• Simplified error handling for export failures in the summary screen. (lib/screens/summary_screen.dart)

Type of change

• Bug fix
• New feature
• Refactor / cleanup
• Documentation
• Other:

Checklist

• flutter analyze passes with no new issues
• flutter test passes
• New or updated strings have translations in all supported locales
• Self-reviewed the diff