👷 ci: attest build provenance for release assets

.github/workflows/release.yaml

@@ -10,6 +10,8 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: write
+      id-token: write
+      attestations: write
     steps:
       - uses: actions/checkout@v5
 
@@ -24,6 +26,14 @@ jobs:
           npm test
           npm run build
 
+      - name: Attest build provenance
+        uses: actions/attest-build-provenance@v3
+        with:
+          subject-path: |
+            main.js
+            manifest.json
+            styles.css
+
       - name: Create release
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}