Expose the resolved Node.js and package manager versions as outputs #198

setup-vp only sets the version and cache-hit outputs. After the step runs, the workflow can't tell which Node.js version or which package manager version it ended up with, even though setup-vp (or vp itself, when node-version is omitted) just picked them.

- id: vp
  uses: voidzero-dev/setup-vp@v1.21.2
- run: echo "node=${{ steps.vp.outputs.node-version }}" # always empty

I need these values for cache keys outside the dependency cache, like node_modules/.vitest-cache and .tsbuild, which should be invalidated when the runtime changes. Right now I read them back from package.json before calling the action:

- id: toolchain
  shell: bash
  run: |
    echo "node=$(jq -er '.devEngines.runtime.version' package.json)" >> "$GITHUB_OUTPUT"
    echo "bun=$(jq -er '.packageManager | capture("^bun@(?<v>[^+]+)").v' package.json)" >> "$GITHUB_OUTPUT"
- uses: voidzero-dev/setup-vp@v1.21.2
  with:
    node-version: ${{ steps.toolchain.outputs.node }}

That only works because both versions in my package.json are exact. With a range, or with node-version left out so Vite+ resolves it (#128, #130), the value I compute and the one that got installed can differ. The matrix example in the README has the same gap: matrix.node-version is "22", not the patch release that was installed.

actions/setup-node has a node-version output and oven-sh/setup-bun has bun-version, so anyone moving from those to setup-vp loses this.

What I have in mind:

vp env current --json already reports all three. Locally, with vp 1.0.0-rc.0 in a project that declares devEngines.runtime and "packageManager": "bun@1.4.2", it prints this (paths removed):

{
  "node": { "version": "24.20.0", "source": "devEngines.runtime", "installed": true, "mode": "managed" },
  "package_manager": { "name": "bun", "version": "1.4.2", "source": "packageManager", "installed": true, "mode": "managed" }
}

So in runMain, after vp env use and the package-manager commands, the action could run vp env current --json with cwd: projectDir and set the outputs from node.version, package_manager.name and package_manager.version. If the command fails or a field is missing, fall back to unknown the way version does in printViteVersion.

From reading resolve_version in vite-plus (crates/vp_global_cli/src/commands/env/config.rs), the vp env use override is checked first (VP_NODE_VERSION, then the session file), and ranges or aliases from project files come back as exact versions. So the output should match what vp env use installed. I haven't checked that on a runner yet; if it turns out not to, node --version through the shim would do for Node.

The JSON layout changed in Vite+ 0.3.1 (voidzero-dev/vite-plus#2398): before that, the Node version was a top-level version field. Gating on supportsScopedEnv, like the package-manager input does, seems simpler than parsing both layouts.

With node-manager: false, reading current.rs it looks like vp env current reports the Node.js found on PATH, which is the right value for node-version in that case too.

Two questions before I write it:

1. GitLab and Azure. The parity table in rfcs/azure-pipelines-integration.md lists "Version/cache-hit outputs", so I'd add the new values to .setup-vp-outputs.env and the Azure job variables as well. SETUP_VP_NODE_VERSION is already a GitLab input, though, so the output needs another name. Would SETUP_VP_INSTALLED_NODE_VERSION (next to SETUP_VP_INSTALLED_VERSION), SETUP_VP_PACKAGE_MANAGER_NAME and SETUP_VP_PACKAGE_MANAGER_VERSION work?
2. Output names on GitHub. node-version matches setup-node and doesn't clash, since inputs and outputs live in separate namespaces. Fine with you, or would you prefer resolved-node-version?

I'm happy to send a PR covering all three integrations, with the rebuilt dist/ bundles and tests next to the changed sources.

This is unrelated to #126: that cache is keyed on the run id and doesn't need runtime versions.