[DaveLiddament]

Summary

• Add executable orb setup and resume scripts for Debian 12's PHP 8.2, required extensions, Xdebug, Composer, and locked development dependencies.
• Reuse installed system packages and Composer dependencies on warm setup; resume only checks platform requirements.
• Disable commit signing only for disposable integration-test repositories under tests/scratchpad, leaving SARB commits signed.
• Document orb development and ignore generated portal metadata.

Verification

• Cold setup: 17.6 seconds; repeated warm runs: 0.4–0.5 seconds with nothing to install.
• Resume: 0.14 seconds; repeated successfully.
• Clean non-interactive login shell verified PHP, Composer, Xdebug, autoloading, and scoped signing settings.
• composer ci passed: 727 tests, 3,396 assertions, 100% coverage, and no PHPStan errors; validation, lint, dump checks, and code style passed.
• bash syntax and git diff whitespace checks passed; both lifecycle scripts have executable permissions.

Setup becomes active for future orbs once merged into master.