@capacitor/android and capacitor-cordova-android-plugins both declare
sourceCompatibility/targetCompatibility VERSION_21. javac rejects
`--release 21` on anything older than JDK 21, which is what the workflow
had configured (17), failing compileReleaseJavaWithJavac.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>