nix: merge all nix programs into applications.nix

modules/applications.nix

@@ -1,5 +1,8 @@
 { config, lib, pkgs, ... }:
 
+let
+  isLinux = pkgs.hostPlatform.system == "linux";
+in
 {
   environment.systemPackages = with pkgs; [
     spotify
@@ -9,5 +12,16 @@
     element-desktop
     keepassxc
     ani-cli
+  ]
+  ++ lib.optionals (pkgs.hostPlatform.system == "linux") [
+    # linux-specific/broken on OSX
+    mpv
+    ghostty
+    thunderbird
+  ]
+  ++ lib.optionals (pkgs.hostPlatform.system == "darwin") [
+    iina
+    utm
+    raycast
   ];
 }