CLOUDPLAT-3162: add npm OIDC publish workflow

https://mapbox.atlassian.net/browse/CLOUDPLAT-3162

Author: haseebehsan

.github/workflows/npm-release.yml

@@ -0,0 +1,15 @@
+name: NPM release
+
+on:
+  workflow_dispatch:
+
+jobs:
+  npm-release:
+    uses: mapbox/gha-public/.github/workflows/workflow-npm-oidc-publish.yml@main
+    permissions:
+      id-token: write
+      contents: write
+    with:
+      create-github-release: true
+      environment: npm-release
+      run-tests: false

CONTRIBUTING.md

@@ -0,0 +1,24 @@
+# Contributing to pixelmatch
+
+## Development
+
+```bash
+npm ci
+npm test
+```
+
+## Releasing a new version
+
+Releases are published to npm via GitHub Actions.
+
+### Steps
+
+1. **Bump the version** in `package.json` (follow [semver](https://semver.org))
+2. **Update `CHANGELOG.md`** with a summary of what changed
+3. **Open a PR**, get it reviewed and merged to `main`
+4. **Trigger the release** from the [Actions tab](../../actions/workflows/npm-release.yml):
+   - Select **NPM release** → **Run workflow** → run from `main`
+
+The workflow will publish to npm and create a GitHub release with auto-generated notes.
+
+> **Note:** Only Mapbox maintainers with write access to this repository can trigger the release workflow. External contributors can open and contribute to PRs, but releases are always cut by the owning team.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "pixelmatch",
-  "version": "7.2.0",
+  "version": "7.2.1",
   "type": "module",
   "description": "The smallest and fastest pixel-level image comparison library.",
   "main": "index.js",
@@ -38,5 +38,8 @@
   "bugs": {
     "url": "https://github.com/mapbox/pixelmatch/issues"
   },
-  "homepage": "https://github.com/mapbox/pixelmatch#readme"
+  "homepage": "https://github.com/mapbox/pixelmatch#readme",
+  "publishConfig": {
+    "access": "public"
+  }
 }