feat: Add local vhost resolution via extraHosts

modules/core/vhost.nix

@@ -73,6 +73,12 @@ in
             default = { };
             description = "An attribute set of location configurations.";
           };
+
+          resolveLocally = mkOption {
+            type = types.bool;
+            default = true;
+            description = "If true, ensure the vhost is resolvable to 127.0.0.1 locally on this server.";
+          };
         };
       });
       default = { };
@@ -114,5 +120,11 @@ in
           conf.locations;
       })
       cfg.hosts;
+
+    networking.extraHosts = concatMapStringsSep "\n"
+      (domain:
+        mkIf cfg.hosts.${domain}.resolveLocally "127.0.0.1 ${domain}"
+      )
+      (lib.attrNames cfg.hosts);
   };
 }