[codex] Add updateDefaultSeries and release automation

[javorosas]

Summary

• add organizations.updateDefaultSeries(...) to the Java SDK with Javadoc and regression coverage
• bump the package version to 1.1.0 and add a repo-level CHANGELOG.md, including the 1.0.0 initial release entry
• update the publish workflow to create or update a GitHub Release and tag from the pom.xml version and matching CHANGELOG.md section

Why

Java was missing updateDefaultSeries, even though the method exists in the other official SDKs and is already documented. The repo also did not record release history locally or automate GitHub Releases from the declared package version.

Impact

Consumers of the Java SDK now get feature parity for organization default-series updates. Release management is also tighter: Maven publish remains gated by pom.xml, while GitHub tags and release notes are derived from the same version and changelog entry.

Validation

• mvn test
• local validation of the changelog extraction and version-gating logic used in .github/workflows/publish.yml