[vitormattos]

Backport of #9457 to stable35

Restores correct exit status handling for the OpenAPI/TypeScript generation command and provides an OpenAPI-only alternative:

• composer run openapi fails when either generator fails.
• composer run openapi:spec regenerates the OpenAPI specification without requiring Node.js.
• Keeps the original six regression cases from fix(openapi): propagate TypeScript generation failures #9457.

Stable branch adaptation

The tests/php/openapi/phpunit.xml test suite introduced on main does not exist on stable35. Place OpenApiGenerationTest.php under tests/php/Unit/ instead, so the pre-existing unit suite discovers it. No change to the stable PHPUnit configuration is needed.

Verification

• Compared branch with stable35: only composer.json and tests/php/Unit/OpenApiGenerationTest.php changed.
• PHP 8.4 CLI synthetic generator checks: 6/6 passed, including errors 23, 37, 127 and success paths.
• Commit created with verified OpenPGP signature and matching DCO sign-off.
• Not run locally: actual PHPUnit suite or full OpenAPI/TypeScript regeneration; CI needs to validate integration in the target branch.

Backport source commit: 83949bb0a69e9bbe12c109aa0618712a17aec7b3.

No automatic merge requested.