Add repository tests for data layer

[MihaiCristianCondrea]

Summary

• add unit tests for the About and Lesson repositories to cover formatting and invalid inputs
• add extensive SettingsRepository tests that mock SharedPreferences, AppCompatDelegate, and FirebaseAnalytics interactions
• cover Help, Support, and Startup repositories with mocked platform services to assert delegation and graceful handling

Testing

• ./gradlew test (fails: Android SDK not available in CI environment)

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https://chatgpt.com/codex/tasks/task_e_68c9763e1d34832db2c55a228b805f5e