split up hopper lab configuration into multiple files

sys/machines/hopper/lab/prometheus.nix

@@ -0,0 +1,33 @@
+{
+  lib,
+  config,
+  ...
+}: {
+  services.prometheus = {
+    enable = true;
+    port = 9001;
+    extraFlags = ["--storage.tsdb.retention.time=30d"];
+    scrapeConfigs = [
+      {
+        job_name = "node";
+        static_configs = lib.singleton {
+          targets = ["127.0.0.1:${toString config.services.prometheus.exporters.node.port}"];
+        };
+      }
+      {
+        job_name = "tailscale_client";
+        static_configs = lib.singleton {
+          targets = ["100.100.100.100"];
+        };
+      }
+    ];
+  };
+
+  services.prometheus.exporters = {
+    node = {
+      enable = true;
+      enabledCollectors = ["systemd"];
+    };
+    systemd.enable = true;
+  };
+}