Add CI release workflow

Add release.yml workflow triggered on GitHub release publication.
It runs npm ci and npm publish with --provenance (SLSA provenance
attestation) and --access public (required for @ably/ scoped packages).
Uses the NPM_TOKEN repository secret for authentication via setup-node's
registry-url configuration.

Author: VeskeR

.github/workflows/release.yml

@@ -0,0 +1,26 @@
+name: Release packages
+
+on:
+  release:
+    types: [published]
+
+jobs:
+  release:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: 'write'
+      id-token: 'write'
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          submodules: true
+      - uses: actions/setup-node@v6
+        with:
+          node-version: '24'
+          registry-url: 'https://registry.npmjs.org'
+      - name: Install dependencies and publish
+        env:
+          NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}
+        run: |
+          npm ci
+          npm publish --provenance --access public