Gitea Runner 6.0.0 removes builtin checkout, requires Gitea 1.26.2

Gitea Runner 6.0.0 removes builtin:checkout, so workflows must use actions/checkout or another checkout action, and it requires Gitea 1.26.2 or newer.

Shared tool caches now use separate caches for each capacity slot, allowing shared mode above capacity one, while cache and artifact address detection now prefers IPv4 for each job.

The release also adds macOS launchd setup guidance and covers 5.x changes including Windows support, FreeBSD Docker jobs, ref-scoped caches, and GITEA_* aliases.