[samson30]

Relates to debezium/dbz#1809

Description

Standardizes offset-editor.

• Uses debezium-examples-parent as parent, so the Java version (21) now comes from the root POM instead of the local Java 11 maven.compiler.source/target settings
• Upgrades JavaFX 16 → 21.0.7, the JavaFX line built for Java 21 (JavaFX 16 is no longer supported)
• Upgrades maven-shade-plugin 3.2.4 → 3.6.0, which supports Java 21 class files
• Updates the README prerequisites to JDK 21 and JavaFX 21
• groupId/artifactId/version are unchanged, so the jar names stay the same

There is no CI workflow for this example, so I verified it locally on JDK 21: mvn clean install succeeds, mvn javafx:run opens the editor, and the shaded jar (java -jar target/offset-editor-1.0-SNAPSHOT-shaded.jar) starts the GUI.

Checklist

• If the changes include a new example, I added it to the list of examples in the README.md file

[Naros]

The PR LGTM, I've just left one small item below on a README change.

[Naros]

Thanks @samson30, applied! 🎉