docs(release): record how the release path is validated

[BharathASL]

Description

Adds RELEASE_PROCESS.md §6, giving the standing rule from #208 a durable home outside the issue that is about to be closed: release.yml is triggered only by a v* tag push and by workflow_dispatch, no pull request ever runs it, and a workflow_dispatch run leaves github.ref on a branch so the publishing step's if: startsWith(github.ref, 'refs/tags/') guard skips it. A bump to an action used only in that workflow therefore cannot be validated by CI, and the rule is that you either exercise the path or say in the pull request that the bump was merged unexercised.

The same section records the exercise itself. v0.1.0-alpha.1 was pushed at 81472f3, the run went green (run), every step executed with none skipped, the release published as a pre-release and not a draft with all five zips attached (512× 223788, 256× 124347, 128× 75243, 64× 42284, 32× 31649 bytes), the body carried the pre-release fallback note above GitHub's generated notes, and the downloaded 512× zip unpacked to a valid pack containing pack.mcmeta, pack.png and 33 PNGs under assets/minecraft/textures/block/. That was the first execution of softprops/action-gh-release v3.0.2 on this repository — the version #23 introduced without CI ever running it. The release and the tag were deleted about two minutes after publishing; gh release list and git ls-remote --tags origin are both empty again.

No distribution channel, secret or upload step was added. LICENSE and §5 are untouched.

Closes #208.

Affected Assets

• RELEASE_PROCESS.md (documentation only; no textures, blockstates or models)

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Type of Change

• feat: New vector texture master, blockstate, or compiler capability
• fix: Tiling fix, palette correction, or bugfix
• docs: Documentation improvement
• chore / refactor: Maintenance, dependencies, or codebase cleanup

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Contributor Checklist

Vector Texture Standards (if adding/modifying SVGs)

Not applicable — no SVGs are touched.

Build & Verification

• The compiled pack was verified, by the release run itself rather than locally: node tools/build.mjs --all produced all five zips and the published 512× zip was downloaded and unpacked.

Git Hygiene & Standards

• Commit message follows Conventional Commits.
• The commit is signed off with the Developer Certificate of Origin (git commit -s).
• Branch is rebased cleanly onto latest main with no merge commits.
• Formatting complies with .editorconfig (2-space indent, LF endings, trailing newline).