Publish sheetz-examples artifact to Maven Central

[chitralabs]

Feature: Publish Examples to Maven Central

Publishing the sheetz-examples project to Maven Central as an artifact would:

1. Add 1 more "used in" dependent for sheetz-core on Maven Central
2. Make examples easily runnable via Maven without cloning

Task:

• Update sheetz-examples/pom.xml with publishing configuration
• Add GPG signing profile (follow sheetz-core pom.xml as template)
• Publish to Maven Central as io.github.chitralabs.sheetz:sheetz-examples:1.0.1