feat: upgrade to Node 24 and modernize build toolchain

[rathpc]

Summary

Upgrade cli-build to Node 24, esbuild bundling (replacing @vercel/ncc), ESLint 10, real unit tests with mocked GitHub Actions deps, and a standardized semantic-release flow with floating major/minor tags. Adds CLAUDE.md.

This is the Wave 2 canary for the broader ontrack-github-actions-* upgrade effort. The recipe validated here will apply to cli-setup, cli-validation, cli-config, and cli-install in subsequent PRs.

What changed

• Runtime: engines.node set to >=24; action.yml runtime is node24; CI workflow installs Node 24.
• Action file: renamed action.yaml → action.yml for consistency across the repo family. runs.using bumped from node16 to node24.
• Bundling: replaced @vercel/ncc with esbuild + esbuild-plugin-license (driven by a small build.js). dist/index.js is now produced by esbuild; dist/licenses.txt carries third-party attributions (matching ncc's --license semantics).
• Source shape: index.js refactored to a dependency-injection pattern. A top-level IIFE loads pure-ESM @actions/* packages via dynamic ESM import and calls an exported runAction({core, exec, github}) function. This pattern is necessary because @actions/core@3, @actions/exec@3, and @actions/github@9 are pure ESM and can no longer be require()'d from CJS.
• Tests: new index.test.js with 14 unit tests covering input handling, fallbacks (project → repo name; branch → ref parse; build → run number), conditional CLI args (release, run-info), setWorkflowRun invocation, and the executable input. Tests run in <200ms without any secrets or network.
• ESLint: eslint 8.x → 10.3.0 with new flat config (eslint.config.mjs). Companion @eslint/js pinned to ^10.0.1 (latest published — the @eslint/js package versions independently from eslint itself).
• Release rules: every conventional-commit type now triggers at least a patch release; BREAKING CHANGE: footer always forces major. New .releaserc matches the standardized template across the repo family.
• Floating tags: new CI step force-updates vX and vX.Y tags after each release, so consumers can pin to @v2 and ride patch updates.
• Docs: new CLAUDE.md; README.md "Building" section updated for esbuild.
• Workflow: old minimal .github/workflows/build.yml (which lacked lint/test/release) replaced by .github/workflows/ci.yml with the standardized template (actions/checkout@v6, actions/setup-node@v6, full lint+build+test+release pipeline).

Why this is breaking

engines.node >= 24 and runs.using: node24 mean self-hosted runners on older Node will fail. GitHub-hosted runners support Node 24 natively. Hence the BREAKING CHANGE: footer in the squash-merge commit, which semantic-release will use to bump this action to 2.0.0.

The action's input/output surface is unchanged. Workflows currently using @v1 continue to work against the existing v1 release (untouched); they need to opt into @v2 to get Node 24.

Test plan

• CI passes on this PR (lint, build, tests; the self-test step is gated to nemerosa owner and won't run from the fork — that's expected)
• After merge, the main build runs semantic-release and creates the v2.0.0 GitHub release
• After release, floating tags v2 and v2.0 exist and point at the new release SHA
• CHANGELOG.md reflects the breaking change
• dist/licenses.txt is generated alongside the bundle

Squash-merge commit message

When merging, please use this exact commit body:

feat: upgrade to Node 24 and modernize build toolchain

- Replace @vercel/ncc with esbuild + esbuild-plugin-license
- Convert index.js to runAction({core,exec,github}) DI pattern
- Bump @actions/* and semantic-release to latest stable
- Migrate to ESLint 10 flat config
- Add 14 unit tests with mocked GitHub Actions deps
- Standardize semantic-release rules (patch on every commit type)
- Add floating major/minor tag step in CI
- Rename action.yaml -> action.yml for consistency
- Add CLAUDE.md for AI-assisted development

BREAKING CHANGE: Now requires Node 24 runtime. Self-hosted runners
must have Node 24 available; GitHub-hosted runners support this
natively. The action's input/output surface is unchanged; consumers
need to bump @v1 -> @v2 to opt in.

[rathpc]

@dcoraboeuf here is the second in the batch following this one nemerosa/ontrack-github-actions-module-install#1

[rathpc]

@dcoraboeuf the workflow was failing previously on the "self-test" step. A change was made to include another gate which should fix the problem. Please run again when you can, thank you!

[dcoraboeuf]

@rathpc, I'm on it.

Side note: please note that since Yontrack V5, there is a new way of configuring your projects: https://docs.yontrack.com/yontrack/ref/latest/content/configuration/ci-config.html. It may worth having a look.

[dcoraboeuf]

Available in v1.0.0

Thanks for your contribution @rathpc !