feat: add PHP version smoke test to CI

[DeepDiver1975]

Summary

• Restructures matrix.version from a flat string array to an object array, mirroring the pattern used in owncloud-docker/ubuntu
• Adds per-version smoke-test-cmd: verifies PHP 7.4 for 22.04 and PHP 8.3 for 24.04
• Passes smoke-test-cmd to the reusable docker-build.yml workflow, which runs it as a one-shot docker run --rm check after the image is built

Test Plan

• CI builds both matrix versions and runs the smoke test step
• php --version | grep -qF 'PHP 7.4' passes for the 22.04 image
• php --version | grep -qF 'PHP 8.3' passes for the 24.04 image

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