almost automatic release to Maven Central

[oetr]

Just push the tag to release.

[Copilot]

Pull Request Overview

This PR automates the release process to Maven Central by replacing manual deployment with an automated API-based upload using a bearer token.

Key Changes:

• Removed manual Maven credentials (username/password) in favor of automated token-based authentication
• Added automatic deployment to Maven Central via Sonatype API with bearer token
• Streamlined release process by removing the draft release step and manual upload requirement

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
deploy/deploy.sh	Removed MAVEN_USER and MAVEN_PASSWORD environment variable checks and parameters from bazel commands, as deployment now uses bearer token authentication
CONTRIBUTING.md	Updated release documentation to reflect automated workflow and provided fallback manual deployment instructions
.github/workflows/prerelease.yaml	Renamed job to maven_deploy, added automated deployment step using Sonatype API with bearer token, changed bundle artifact to tar.gz format, and removed draft flag from release creation

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[simonresch]

Thanks! LGTM.