Related tasks for Alpine (musl) x64 promotion to Tier 2

Current status

Platform list currently contains the following entry:

Other architectures are unlisted, and have no designated support type.

Official binary platforms and toolchains does not list any Alpine / musl build.

node Docker images for Alpine are built from https://unofficial-builds.nodejs.org/download/release/v<node-version>/node-v<node-version>-linux-x64-musl.tar.xz

• Alpine x64 images are built using the x64-musl build directly
• Alpine arm64, arm32 and s390x images are built from source

Update automation treats security releases differently and proceeds with these releases without waiting for musl build availability.

Proposed Node.js change

PR https://github.com/nodejs/node/pull/63737 proposes the promotion of Alpine/x64 to Tier 2.

This can be expected to add Alpine/x64 to the Platform list and to Official binary platforms and toolchains.

An x64-musl build can be expected to be available through the regular https://nodejs.org/download/release/ website.

Impact

Expected update tasks and impact will include:

• Documentation README references to support category and process
• Dockerfile-alpine.template to source the musl build from https://nodejs.org/download/release/
• update.sh script so that the -s (security) option does not exclude Alpine builds, or for more simplification, remove the -s option entirely, since it becomes a no-op
• build-automation.mjs remove checks against https://unofficial-builds.nodejs.org

Review other Alpine-related issues and PR for relevance and applicability.

Start with README, Dockerfile-alpine.template, update.sh, and build-automation.mjs, then review the linked Node.js promotion and other Alpine issues. Update the documented support process, use the regular Node.js release source for Alpine x64, and remove obsolete unofficial-builds checks and security-release handling when the Tier 2 promotion is in place.