Add rollback-sentinel NixOS module that:
- Deploys sentinel-check.sh (inline) and nixos-rollback.sh (from file) as
system packages
- Runs a boot-time systemd oneshot service after multi-user.target with
configurable delay — checks Tier-1 services, triggers rollback on failure
- Runs a post-rebuild service via activation script after every
nixos-rebuild switch
- Exposes options for tier1Services, tier2Services, tier3InfoServices,
bootDelay, rollbackMode (set-default/rollback-now/dry-run), and
enablePostRebuild
Module wired into flake.nix for lazyworkhorse and enabled in
configuration.nix with standard Tier-1/2 service lists and 120s delay.
Hermes
aa4a3f5b7c