flake.nix: structure overhaul

hosts/dunamis/disko.nix: add tmpfs mount for /tmp (nix builds fail because of noexec on /)
modules/home/desktop/default.nix: remove walker

Signed-off-by: unexplrd <unexplrd@linerds.us>

hosts/dunamis/disko.nix

@@ -2,6 +2,12 @@
   imports = with inputs; [
     disko.nixosModules.disko
   ];
+  disko.devices.disk.nodev = {
+    "/tmp" = {
+      fsType = "tmpfs";
+      mountOptions = ["rw" "nosuid" "nodev"];
+    };
+  };
   disko.devices.disk.main = {
     type = "disk";
     device = "/dev/nvme0n1";