Wire the previously-unregistered Gemini CLI HostConfig into the registry.
The rescued config reused Codex's .agents hostSubdir, which collides with
codex under validateAllConfigs (hostSubdir/globalRoot must be unique).
Retarget Gemini to its native .gemini home (matching its GEMINI.md rewrite
and Google's Gemini CLI convention) and bump the host-count assertion 10 -> 11.