Use dedicated release runner (runs-on: release)

Release builds now run on moko-beelink-release, a dedicated runner
that won't compete with CI jobs for capacity.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.github/workflows/release.yml

@@ -47,7 +47,7 @@ env:
 jobs:
   build:
     name: Build Release Package
-    runs-on: ubuntu-latest
+    runs-on: release
 
     steps:
       - name: Checkout repository