Move drop and try to get it working.

nodes/hosts/common/programs/drop.nix

@@ -1,11 +1,11 @@
 { pkgs, lib, inputs, ... }:
 
 let 
-  dropApp = import ../../../../appimages/drop.nix { inherit pkgs; };
+  dropApp = import ./appimages/drop.nix { inherit pkgs; };
 in
 {
   # ...
-  environment.systemPackages = [
-    pkgs.dropApp
+  environment.systemPackages = with pkgs; [
+    dropApp
   ];
 }