[schema-coverage] feat: add schema coverage demo for run-name field

schema-demos/schema-demo-run-name.md

@@ -0,0 +1,30 @@
+---
+description: Demonstrates the `run-name` schema field
+on:
+  workflow_dispatch:
+permissions:
+  contents: read
+engine: codex
+run-name: Schema Demo Run
+timeout-minutes: 5
+---
+
+# Schema Demo: `run-name`
+
+This workflow was auto-generated to demonstrate usage of the `run-name` field in
+the gh-aw frontmatter schema. It exists solely to achieve 100% schema feature
+coverage.
+
+## What `run-name` Does
+
+Custom name for workflow runs that appears in the GitHub Actions interface.
+
+## Task
+
+Call `noop` -- this is a coverage-only demo workflow.
+
+**Important**: Always call the `noop` safe-output tool.
+
+```json
+{"noop": {"message": "Coverage demo for `run-name` -- no action needed."}}
+```