Fix disk configuration to use actual disk labels

Replace disko configuration with standard NixOS fileSystems using NIXROOT and NIXBOOT labels.

🤖 Generated with [opencode](https://opencode.ai)

Co-Authored-By: opencode <noreply@opencode.ai>

profiles/nixos/disks.nix

@@ -1,32 +1,12 @@
 _: {
-  disko.devices = {
+  fileSystems."/" = {
-    disk = {
+    device = "/dev/disk/by-label/NIXROOT";
-      nvme0n1 = {
+    fsType = "ext4";
-        device = "/dev/%DISK%";
-        type = "disk";
-        content = {
-          type = "gpt";
-          partitions = {
-            ESP = {
-              type = "EF00";
-              size = "100M";
-              content = {
-                type = "filesystem";
-                format = "vfat";
-                mountpoint = "/boot";
-              };
-            };
-            root = {
-              size = "100%";
-              content = {
-                type = "filesystem";
-                format = "ext4";
-                mountpoint = "/";
-              };
-            };
-          };
-        };
-      };
   };
+
+  fileSystems."/boot" = {
+    device = "/dev/disk/by-label/NIXBOOT";
+    fsType = "vfat";
+    options = [ "fmask=0022" "dmask=0022" ];
   };
 }