feat(whitby): Enable Gerrit & cgit deployments

Change-Id: Ic701552e130252cfff005938d9c4e98423a7a96a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/1069
Reviewed-by: lukegb <lukegb@tvl.fyi>
Tested-by: BuildkiteCI

ops/nixos/www/code.tvl.fyi.nix

@@ -0,0 +1,27 @@
+{ config, ... }:
+
+{
+  imports = [
+    ./base.nix
+  ];
+
+  config = {
+    services.nginx.virtualHosts.cgit = {
+      serverName = "code.tvl.fyi";
+      enableACME = true;
+      forceSSL = true;
+
+      extraConfig = ''
+        # Static assets must always hit the root.
+        location ~ ^/(favicon\.ico|cgit\.(css|png))$ {
+           proxy_pass http://localhost:2448;
+        }
+
+        # Everything else hits the depot directly.
+        location / {
+            proxy_pass http://localhost:2448/cgit.cgi/depot/;
+        }
+      '';
+    };
+  };
+}