add forgejo-runner on forgejo vm

hosts/forgejo-runner-1/forgejo-runner.nix

@@ -0,0 +1,25 @@
+{ pkgs, ... }:
+{
+  config = {
+    environment.systemPackages = with pkgs; [
+      forgejo-runner
+    ];
+
+    # https://wiki.nixos.org/wiki/Forgejo
+
+    services.gitea-actions-runner = {
+      package = pkgs.forgejo-actions-runner;
+      instances.default = {
+        enable = true;
+        name = "cccb";
+        url = "https://git.berlin.ccc.de";
+        # Obtaining the path to the runner token file may differ
+        # tokenFile should be in format TOKEN=<secret>, since it's EnvironmentFile for systemd
+        tokenFile = "/etc/forgejo-runner/registration_token";
+        labels = [
+          "ubuntu-latest:docker://node:22-bookworm"
+        ];
+      };
+    };
+  };
+}