Remove Python CI/CD workflows — project is now Java only

Removed: ci.yml, beta.yml, publish.yml, sbom.yml, sonarcloud.yml
Kept: ci-java.yml, beta-java.yml, release-java.yml, sonarcloud-java.yml

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

Author: aksOps