[ci] Keep required tests reporting after wiki pointer commits (#230)

[coisa]

Related Issue

Closes #230

Motivation / Context

• Wiki preview automation commits .github/wiki pointer updates back to PR branches.
• The tests workflow previously used a top-level pull_request.paths filter, so a wiki-pointer-only head commit could skip the workflow entirely.
• Branch protection still expects Run Tests (8.3), Run Tests (8.4), and Run Tests (8.5), leaving those contexts stuck as Expected.

Changes

• Removed the top-level pull_request.paths filter from .github/workflows/tests.yml so required test contexts are always reported for PR updates.
• Kept same-PR test workflow runs cancelable, so the newest PR SHA owns the required contexts without making maintainers wait for superseded runs.
• Restored pull_request triggering in the packaged consumer test wrapper.
• Documented the branch-protection/wiki-pointer contract and added a changelog entry.

Verification

• composer dev-tools
• Focused command(s):
  • ruby -e 'require "yaml"; %w[.github/workflows/tests.yml resources/github-actions/tests.yml].each { |f| YAML.load_file(f); puts "#{f} OK" }'
  • composer dev-tools code-style -- --fix --json
  • composer dev-tools changelog:check
  • git diff --check
• Manual verification: after this PR ran in GitHub Actions, the required Run Tests (8.3), Run Tests (8.4), and Run Tests (8.5) contexts were created and completed successfully instead of staying Expected.

composer dev-tools was not run locally because this branch changes GitHub Actions/docs only and the local full gate still runs the heavy reports/metrics path; the workflow syntax was validated directly.

Documentation / Generated Output

• README updated
• docs/ updated
• Generated or synchronized output reviewed

No generated docs/wiki output was committed.

Changelog

• Added a notable CHANGELOG.md entry

Reviewer Notes

• The key behavior is that GitHub branch protection cannot wait on missing contexts anymore: the workflow triggers and the required matrix jobs always exist for pull request updates.
• This intentionally favors reliability of required checks over path-filter optimization.

[github-actions]

🚀 Preview is available for this pull request.

• Docs: https://php-fast-forward.github.io/dev-tools/previews/pr-231/
• Coverage: https://php-fast-forward.github.io/dev-tools/previews/pr-231/coverage/
• Metrics: https://php-fast-forward.github.io/dev-tools/previews/pr-231/metrics/