chore: add GitHub Packages publication

[Osilvfe]

Thirty-sixth integration/distribution pass

• make the Maven publication version configurable through AMLL_VERSION or -PamllVersion, while retaining 0.1.0-SNAPSHOT for local development
• normalize release-style versions by removing a leading v
• register the repository-scoped GitHub Packages Maven endpoint only when both GITHUB_ACTOR and GITHUB_TOKEN are present, so ordinary local and PR builds stay credential-free
• add a dedicated package workflow triggered by a published GitHub Release or manual dispatch
• run unit tests and assemble the release AAR before publishing
• grant the publishing workflow only contents: read and packages: write

This prepares dev.yaqmc:amll-android for consumption by the separate private YAQMC/YAQMC repository. Cross-repository consumption still requires that repository to have package read access (or a PAT classic with read:packages), which will be handled on the YAQMC integration side rather than coupling credentials into this library PR.