[vitormattos]

Summary

Remove the remaining runtime dependencies on LibreCodeCoop/github-workflows.

• materialize the current organization appstore-build-publish.yml, which now uses release-tool v0.11.1 for package validation and App Store verification;
• materialize the current workflow synchronization template, which uses the helper owned by LibreCodeCoop/.github;
• keep the repository-specific manual release workflow local, but replace the historical release-plan Action with release-tool v0.11.2 release:preflight;
• pass the selected stable branch explicitly as the checked release ref, avoiding the old GITHUB_REF_NAME=main mismatch after checkout.

After this merges, the repository no longer requires release/runtime code from LibreCodeCoop/github-workflows.