[Kevin Rudde (kevinrudde)]

This pull request updates the PHP build matrix and refactors the Docker build and automation scripts to improve maintainability and ensure alignment with upstream sources. The most important changes are grouped below:

Build Matrix and Version Management Updates:

• Updated the phpMatrix and frankenphpMatrix variables in docker-bake.hcl to use the latest PHP patch versions: 8.2.35, 8.3.36, 8.4.27, and 8.5.12.
• Added new variables to docker-bake.hcl for tracking the upstream references: phpLibraryRef (commit SHA of docker-library/php), frankenphpRef (FrankenPHP version), and goVersion.

Docker Build Target Refactoring:

• Refactored build targets in docker-bake.hcl to use custom build contexts based on the upstream phpLibraryRef and to build PHP from source using upstream Dockerfiles. Added new targets: php-fpm-alpine, php-zts-trixie, and frankenphp-upstream.
• Updated the frankenphp and fpm targets to use the new upstream-based targets as their base, enabling more consistent and reproducible builds. [1] [2]
• Changed the frankenphp/Dockerfile to use FROM base instead of a tag-based image, reflecting the new multi-stage build approach.

Automation Script Improvements:

• Refactored update-php-matrix.mjs to fetch the latest PHP patch versions and the upstream commit SHA directly from GitHub, replacing Docker Hub API usage. The script now updates phpMatrix, frankenphpMatrix, and phpLibraryRef in docker-bake.hcl automatically.

These changes streamline the process of keeping PHP versions up to date, ensure that builds are based on the latest upstream sources, and improve automation reliability.