install chatgpt desktop and fix default applications

modules/capabilities/ai.nix

@@ -103,6 +103,7 @@ in
         pkgs.nodejs
         pkgs.python3
         inputs.llm-agents.packages.${pkgs.stdenv.hostPlatform.system}.codex
+        pkgs.llm-agents.chatgpt
         pkgs.llm-agents.pi
         pkgs.llm-agents.claude-code
         pkgs.llm-agents.agent-deck

modules/capabilities/desktop-defaults.nix

@@ -67,7 +67,7 @@
   };
 
   flake.modules.homeManager.workstation-apps =
-    { pkgs, ... }:
+    { lib, pkgs, ... }:
     {
       home.packages = with pkgs; [
         spotify
@@ -77,6 +77,7 @@
         pinta
         zellij
       ];
+      xdg.mimeApps.defaultApplicationPackages = lib.mkAfter [ pkgs.onlyoffice-desktopeditors ];
     };
 
   flake.modules.homeManager.xdg =

modules/capabilities/neovim/default.nix

@@ -224,5 +224,6 @@ in
         VISUAL = "nvim";
       };
       xdg.mimeApps.defaultApplicationPackages = [ pkgs.neovim ];
+      xdg.mimeApps.defaultApplications."text/markdown" = "nvim.desktop";
     };
 }