feat(reverse-proxy): add Pikachu reverse proxy guest

lib/guests.nix

@@ -3,6 +3,7 @@
   self,
   specialArgs,
   bridgeName,
+  reverseProxyRoutes,
 }:
 let
   inherit (lib) escapeShellArg mapAttrsToList;
@@ -130,6 +131,10 @@ let
             guest takes its address by DHCP, keeping IP management at the router.
           '';
         };
+        reverseProxy = reverseProxyRoutes.mkRouteOptions {
+          subject = "guest route";
+          enableDefault = false;
+        };
         mounts = lib.mkOption {
           type = lib.types.attrsOf (
             lib.types.submodule {
@@ -273,6 +278,10 @@ let
       config = lib.mkIf cfg.enable {
         sops.secrets = lib.genAttrs cfg.secrets (_: { });
 
+        modules.reverse-proxy.routes.${machineName} = lib.mkIf cfg.reverseProxy.enable (
+          reverseProxyRoutes.routeFields cfg.reverseProxy
+        );
+
         assertions = [
           {
             assertion = mountCollisions == [ ];