Repair wp/6.3 branch Actions: Add a mariadbVersion option to wp-env - #83818

Part of #82930.

What?

Adds a mariadbVersion option to .wp-env.json and a WP_ENV_MARIADB_VERSION environment variable to wp-env, so the MariaDB version it uses can be chosen.

• The option can be set at the top level of .wp-env.json or per environment (env.development, env.tests), like phpVersion. WP_ENV_MARIADB_VERSION overrides both environments.
• Accepted values are "lts", "latest", or a numeric version such as "10.11" or "11.4.2". Anything else fails validation, in the config file or the environment variable.
• Unset keeps today's floating mariadb image exactly as it is; a set version becomes mariadb:<version>.
• The option is documented in the README, and packages/env/CHANGELOG.md gets an entry.
• The README says to run wp-env destroy before switching to a lower version, and that it removes the environment's Docker containers, volumes, networks, images, and local files, not only the databases. Its ARM note covers MariaDB 5.5 only (10.0 has ARM images) and says that DOCKER_DEFAULT_PLATFORM runs every container under emulation.

Why?

This branch's wp-env (8.1.3) always runs a floating MariaDB image, which keeps moving to releases far newer than anything WordPress 6.3 was released against. There's no way to pin an era-appropriate version for testing. #83827, later in this stack, uses this option to do that.

How?

This ports #83751. This branch has no schemas/json/wp-env.json and no database health check, so neither applies; only the image tag in lib/build-docker-compose-config.js changes. The config parsing, environment variable and validation (checkMariaDBVersion()) match trunk, adapted to this branch's files. #83751's downgrade error and stricter phpVersion check are not ported. Its wp db client wrappers come later in this stack, in #83868.

The unit tests for the validator, the config parsing and the compose output are ported too, and the config snapshot gains "mariadbVersion": null.

Use of AI Tools

This PR was created by Claude Code under my supervision. All code should be treated as AI-produced and not yet reviewed by a human until this PR is marked Ready for Review.

🤖 Generated with Claude Code