feat: achieve 100% unit test coverage with performance regression guards

[devin-ai-integration]

Summary

Adds comprehensive unit tests across all components, services, interceptors, pipes, and directives — going from ~6 service-only spec files to 33 spec files with 447 tests achieving 100% line/branch/function/statement coverage.

New spec files (27): auth component, if-authenticated directive, 3 interceptors, footer/header layout, 5 article shared components, 3 article page components, 4 profile components/pages, profile routes, settings component, app component/config/routes, list-errors component, 2 pipes.

Expanded: user.service.spec.ts with error handling (4XX/5XX), exponential backoff retry logic, getCurrentUserSync(), and auth state observable tests.

Config changes:

• vitest.config.ts: Added 100% coverage thresholds for lines/functions/branches/statements
• package.json: Added test:coverage:ci script (vitest run --coverage)
• Added @vitest/coverage-v8 and zone.js as dev dependencies

Review & Testing Checklist for Human

• @angular/core version drift in bun.lock: The lockfile resolved @angular/core to 21.2.4 while package.json pins other @angular/* packages at 21.1.1. Verify this mismatch doesn't cause peer dependency issues or subtle runtime differences. Consider whether this bump was intentional or a side effect of bun install.
• Coverage threshold sustainability: All thresholds are set to 100%. Confirm that .html and .css template files (which show 0% in the report) are properly excluded from threshold enforcement, and that adding new source files won't break CI until tests are added.
• Mock fidelity in tests: Many test files use as any for service mocks rather than typed mocks. Spot-check a few specs (e.g., article.component.spec.ts, profile.component.spec.ts) to verify the mocks reflect actual service interfaces and that tests exercise real component logic rather than just the mocks.
• provideAppInitializer integration test: The test in app.config.spec.ts bootstraps TestBed with the full appConfig.providers to cover lines 74-77. Verify this test isn't flaky — it relies on ApplicationInitStatus.donePromise resolving and the real JwtService/UserService initializing in jsdom.

Recommended test plan: Run bun run test:coverage:ci locally and confirm the coverage report shows 100% across all .ts files with exit code 0. Then try adding a new untested function to any source file and verify the threshold enforcement fails the run.

Notes

• Tests follow existing repo conventions: Vitest with jsdom, zone.js imports, TestBed with beforeAll + initTestEnvironment pattern required by the pool: 'threads' config.
• No production source code was modified — only test files and config.
• The beforeAll / initTestEnvironment pattern means each spec file must initialize TestBed exactly once. Files with multiple describe blocks only call it in the first block.

Link to Devin session: https://app.devin.ai/sessions/8727d068b98941bfa16cb82f11b76ee3
Requested by: @dr-phil

[devin-ai-integration]

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