feat(hil): make hil11 a stable runner

[sky-mart]

it means that it won't take reflashing jobs from orb-os but only jobs from orb-software or orb-core

[github-actions]

• Blocking – nix/machines/hil-common.nix:383: Changing the platform label does not restrict repository access. orb-os can still schedule hil11 via generic/default labels or its hostname because it remains in the shared hardware-in-the-loop-server runner group. To guarantee only orb-software and orb-core jobs run here, use a runner group whose repository access is limited to those repositories.

[github-actions]

• Blocking — nix/machines/worldcoin-hil-munich-11/configuration.nix:21: Changing extraLabels will not update the already-registered runner during nixos-rebuild switch, because hil-common.nix sets restartIfChanged = false. Hil11 will therefore keep its existing worldcoin-hil-pearl label and continue accepting orb-os jobs until the runner is explicitly restarted/re-registered. The deployment needs a safe mechanism to apply this label change.