corenix: update uwu config to chainload grub

infra/corenix/configs/kookie/uwu.nix

@@ -10,14 +10,16 @@
     extraConfig = ''
       menuentry "NixOS" {
         cryptomount -u f1440abd-99e3-46a8-aa36-7824972fee54
-        search --set=drive1 --fs-uuid 672c497c-18aa-4b00-ac95-78e810363d81
-        set root=$drive1
-        configfile /grub/grub.cfg
+        search --set=cryptdrive --fs-uuid 672c497c-18aa-4b00-ac95-78e810363d81
+        configfile ($cryptdrive)/grub/grub.cfg
       }
     '';
   };
   
-  seabios.asSecondaryPayload = true;
+  seabios = {
+    enable = true;
+    asSecondaryPayload = true; 
+  };
 
   corenix = {
     corebootConfig = {
@@ -25,6 +27,6 @@
       CONFIG_LINEAR_FRAMEBUFFER_MAX_HEIGHT = "768";
     };
     
-    extraFiles."background.png".src = lib.mkForce ./splash.jpg;
+    extraFiles."background.jpg".src = lib.mkForce ./splash.jpg;
   };
 }