Migrate from OSSRH to Central Publishing Maven Plugin

[boronine-bot]

Summary

OSSRH was shut down on June 30, 2025. This PR migrates the project to the new Central Publishing infrastructure.

Changes

pom.xml:

• Replaced nexus-staging-maven-plugin (1.6.13, legacy OSSRH) with central-publishing-maven-plugin (0.11.0)
• Removed distributionManagement section (no longer needed)
• Configured autoPublish: true and waitUntil: published

README.md:

• Updated deployment docs links to new Central Publishing pages
• Replaced OSSRH credential setup with Portal token authentication instructions
• Simplified deploy command (no more -P release)
• Removed redacted credentials from README

What still needs attention after merge

1. Generate a Portal token at https://central.sonatype.com and add to ~/.m2/settings.xml
2. Verify you can log into https://central.sonatype.com and see the org.hsluv namespace
3. Verify your GPG signing key is still accessible

Verification

mvn clean test passes with zero failures.