feat(test): configurable screenshot and viewTree artifact modes

[padmarajnidagundi]

Summary

Adds configurable test artifact capture modes to improve QA workflows and reporting flexibility.

What changed

• Added screenshot config option with modes: on | on-failure | off.
• Expanded viewTree config option to support: on | on-failure | off.
• Updated fixture attachment logic to use mode-based decisions:
  • Screenshots can now be attached for every test or only failures.
  • Accessibility view-tree JSON can now be attached for every test or only failures.
• Added unit tests for mode validation and attach behavior.
• Updated docs in README and fixture docs.

Why this helps QA

• Enables always-on artifacts for audits and flaky-test triage.
• Keeps CI lean by allowing failure-only artifact capture.
• Standardizes behavior across screenshot and view-tree artifacts.

Validation

• npm run build
• npx playwright test --config=tests/mobilewright.config.ts packages/mobilewright/src/config.test.ts packages/test/src/fixtures.test.ts

Both passed locally.