Add and organize test assets

shell.nix

@@ -2,5 +2,6 @@
   pkgs.mkShell {
     nativeBuildInputs = with pkgs.buildPackages; [
         go
+        caddy
     ];
 }

test_assets/Caddyfile

@@ -0,0 +1,8 @@
+http://localhost:8001 {
+  forward_auth http://localhost:8080 {
+    uri /auth
+  }
+
+  templates
+  respond `Hello, {{.Req.Header.Get "Remote-User"}}`
+}