pr-check.yml: 'Detect platform' now reads the public MokoGitea /metadata
endpoint (retires the manifest.xml / /manifest-field lookup).
auto-release.yml: 'Rename branch to rc' now points rc via git push instead
of branch_rename.php's PATCH /git/refs (which 405s on protected branches).
Surgical step swaps only; branch-policy and platform-specific logic untouched.