ci: delegate Test and Measure to shared wp-ci orchestrator

[Adi-ty]

Description

Replace the self-contained Test and Measure workflow with a thin caller that delegates to rtCamp/wp-shared-workflows/.github/workflows/wp-ci.yml@release/v1.0.0.

Technical Details

• .github/workflows/test-measure.yml — Collapses all jobs (pre-run, lint-css/lint-js/lint-php, unit-tests-js/unit-test-php, build-prod) into a single ci: job using uses: rtCamp/wp-shared-workflows. Matrix: PHP 8.2–8.4 × WP 6.5–7.0 with PHP 8.4 / WP <6.7 excluded. Relies on WP_FRAMEWORK_REPO_TEMP_TOKEN for private repo access.
• .github/bin/determine-modified-files-count.js — Removed (no longer needed).

Checklist

• CI delegates lint, test, and build to rtCamp/wp-shared-workflows
• Removed inline change-detection logic and obsolete JS script