feat: add reusable coverage-badge action

README.md

@@ -16,8 +16,8 @@ revision.
 
 ## Use In Other Repositories
 
-Vociferate ships two composite actions that together cover the full release flow.
-Until release tags are created, reference `@main`. Once tags exist again, pin both actions to the same released tag.
+Vociferate ships three composite actions covering release preparation, release publication, and coverage badge publishing.
+Until release tags are created, reference `@main`. Once tags exist again, pin all actions to the same released tag.
 
 ### `prepare` — update files, commit, and push tag
 
@@ -109,6 +109,26 @@ assets after it runs:
       --data-binary "@dist/myapp"
 ```
 
+### `coverage-badge` - publish coverage report and badge
+
+Run your coverage tests first, then call the action to generate `coverage.html`, `coverage-badge.svg`, and `coverage-summary.json`, upload them to S3-compatible storage, and emit output URLs.
+
+```yaml
+- name: Run tests with coverage
+  run: go test -covermode=atomic -coverprofile=coverage.out ./...
+
+- id: coverage
+  uses: git.hrafn.xyz/aether/vociferate/coverage-badge@main
+  with:
+    artefact-bucket-name: ${{ vars.ARTEFACT_BUCKET_NAME }}
+    artefact-bucket-endpoint: ${{ vars.ARTEFACT_BUCKET_ENDPONT }}
+
+- name: Print coverage links
+  run: |
+    echo "Report: ${{ steps.coverage.outputs.report-url }}"
+    echo "Badge: ${{ steps.coverage.outputs.badge-url }}"
+```
+
 ## Why The Name
 
 > **vociferate** _(verb)_: to cry out loudly or forcefully.