[dmikusa]

Summary

Adds a new multi-implementation workflow set for repositories that package a combined buildpack plus one buildpack per component, such as jvm-vendors and build-tools.

Repositories provide a multi-implementation.json at the repository root:

{
  "combined": "build-tools",
  "integration": false,
  "libpak-tools": {
    "command": "build-build-tools",
    "artifact-flag": "tools",
    "include-all-flag": "include-all-tools"
  },
  "buildpacks": [
    { "name": "build-tools", "image": "build-tools" },
    { "name": "leiningen", "image": "leiningen-dev" }
  ]
}

The set includes:

• create-draft-release.yml — derives the release-note matrix from the config, uses the full release notes action for the combined buildpack and jam summarize for components, and optionally runs integration tests (config integration flag)
• push-buildpackage.yml — derives the push matrix and image names from the config
• update-dependencies-from-metadata.yml — the shared template plus the has-warnings check that jvm-vendors previously carried locally
• scripts/package.sh — generic packaging driven by the config and libpak-tools
• the remaining implementation workflows and scripts

It also updates bootstrap.sh, sanity.sh and the README for the new set.

Follow-up PRs will switch jvm-vendors and build-tools to this set.

Note

This PR was written by opencode and reviewed by a human.