feat(services): openrgb + restic toggles; close out the opt-in services item

Finishing the four remaining "opt-in services" candidates — but two of
them aren't service-shaped, so the package-vs-toggle principle applies:

  - Nextcloud client  → a bare tray app; already in the app-suite menu,
                        not a service.
  - WireGuard         → NetworkManager (on distro-wide) imports .conf
                        tunnels natively, so there's no daemon to "just
                        enable". Only the wg/wg-quick CLI is missing →
                        wireguard-tools added to the app-suite menu.

The two that ARE config-backed become nomarchy.services.* toggles:

  - openrgb → services.hardware.openrgb (daemon + device udev rules).
  - restic  → a small scaffolded surface (repository / passwordFile /
              paths) over services.restic.backups: daily timer, 7/4/6
              retention, --exclude-caches, repo auto-init. Asserts that
              repository + passwordFile are set when enabled. passwordFile
              is typed `str`, not `path`, so a flake-relative secret can't
              be copied into the world-readable store.

README option table and ROADMAP (services now "Seventeen shipped";
cloud-sync / networking / backup / devices areas updated) + the downstream
system.nix examples. Both branches eval-verified; the restic assertions
confirmed firing when repo/password are unset.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

modules/nixos/services.nix

@@ -76,6 +76,47 @@ in
     printing.enable = lib.mkEnableOption ''
       CUPS printing with Avahi/mDNS, so network printers are auto-discovered
       (add vendor drivers via `services.printing.drivers`)'';
+
+    openrgb.enable = lib.mkEnableOption ''
+      the OpenRGB daemon and GUI for controlling RGB lighting on peripherals
+      and (where supported) motherboards — installs the udev rules for device
+      access. Some motherboard controllers also need `hardware.i2c.enable`'';
+
+    restic = {
+      enable = lib.mkEnableOption ''
+        a scheduled (daily) restic backup — headless, complementing the Pika
+        GUI. Backs up `paths` with sane retention (7 daily / 4 weekly /
+        6 monthly); needs a `repository` and a `passwordFile` (below)'';
+
+      repository = lib.mkOption {
+        type = lib.types.str;
+        default = "";
+        example = "/mnt/backup/restic";
+        description = ''
+          The restic repository as a path or URL — e.g. `/mnt/backup/restic`,
+          `sftp:user@host:/srv/restic`, `b2:bucket:/path`. Required when
+          `restic.enable` is set.
+        '';
+      };
+
+      passwordFile = lib.mkOption {
+        type = lib.types.nullOr lib.types.str;
+        default = null;
+        example = "/etc/nomarchy/restic-password";
+        description = ''
+          Path to a file holding the repository password. Give an absolute
+          path that lives ON THE MACHINE — not a `./file` in the flake, which
+          would copy the secret into the world-readable Nix store. Required
+          when `restic.enable` is set.
+        '';
+      };
+
+      paths = lib.mkOption {
+        type = lib.types.listOf lib.types.str;
+        default = [ "/home" ];
+        description = "Paths to include in the backup.";
+      };
+    };
   };
 
   config = lib.mkMerge [
@@ -204,5 +245,34 @@ in
         openFirewall = true;
       };
     })
+
+    (lib.mkIf cfg.openrgb.enable {
+      services.hardware.openrgb.enable = true;
+    })
+
+    (lib.mkIf cfg.restic.enable {
+      assertions = [
+        {
+          assertion = cfg.restic.repository != "";
+          message = "nomarchy.services.restic.repository must be set when restic is enabled.";
+        }
+        {
+          assertion = cfg.restic.passwordFile != null;
+          message = "nomarchy.services.restic.passwordFile must be set when restic is enabled.";
+        }
+      ];
+      services.restic.backups.nomarchy = {
+        repository = cfg.restic.repository;
+        passwordFile = cfg.restic.passwordFile;
+        paths = cfg.restic.paths;
+        initialize = true; # create the repo on first run if it doesn't exist
+        extraBackupArgs = [ "--exclude-caches" ];
+        pruneOpts = [ "--keep-daily 7" "--keep-weekly 4" "--keep-monthly 6" ];
+        timerConfig = {
+          OnCalendar = "daily";
+          Persistent = true; # catch up a missed run after downtime
+        };
+      };
+    })
   ];
 }