Improve test coverage with comprehensive unit tests

[devin-ai-integration]

Add comprehensive unit tests for components, services, and pipes

Summary

This PR adds unit test coverage to the Angular 2 HN application, which previously had no test files. The changes include 14 new spec files covering all major components, services, and pipes in the application.

Tests added for:

• Services: SettingsService (settings management, theme, localStorage persistence), HackerNewsAPIService (API method signatures)
• Components: AppComponent, HeaderComponent, FooterComponent, SettingsComponent, FeedComponent, ItemComponent, ItemDetailsComponent, CommentComponent, UserComponent, LoaderComponent, ErrorMessageComponent
• Pipes: CommentPipe (comment count formatting)

Config changes:

• Updated karma.conf.js with a ChromeCI custom launcher that includes --no-sandbox flag for CI environments

Review & Testing Checklist for Human

• Verify tests pass in CI - Tests could not be run locally due to Chrome headless issues in the dev environment. The code compiles but tests need to be verified in CI.
• Review karma.conf.js changes - The custom launcher configuration and indentation changes should be reviewed for consistency with project standards
• Check test quality for HackerNewsAPIService - Tests verify observables are returned but don't mock actual HTTP responses; consider if deeper testing is needed
• Verify AppComponent GA tracking test - The Google Analytics test is shallow and doesn't fully verify tracking behavior

Recommended test plan:

1. Wait for CI to run and verify all tests pass
2. Run npm test locally if you have Chrome available to verify test execution
3. Check code coverage report if available in CI

Notes

• Pre-existing lint errors in the codebase were not addressed (out of scope for test coverage task)
• Test files have minor deprecation warnings about RxJS subscribe usage that don't affect functionality

Link to Devin run: https://app.devin.ai/sessions/98a4576126814a03b791c4d3ebd0a645
Requested by: Chase Dalton (chase.dalton@cognition.ai)

[devin-ai-integration]

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