feat(kitty): add kitty +kitten ssh as default SSH URL handler

[Bad3r]

Summary

Configure kitty +kitten ssh as the default handler for ssh:// URLs via XDG mimeapps.

Background

The kitty SSH kitten provides enhanced SSH functionality:

• Automatic shell integration on remote hosts
• Copies terminfo files automatically
• Reuses existing connections
• Can copy local config files to remote

Documentation: /home/vx/git/kitty/docs/kittens/ssh.rst

Implementation Requirements

1. Wrapper script to parse ssh:// URLs

   • Input: ssh://[user@]host[:port][/path]
   • Output: kitty +kitten ssh [user@]host [-p port]

2. Desktop file for x-scheme-handler/ssh

3. Module location: Either modules/hm-apps/kitty.nix or new modules/hm-apps/kitty-ssh.nix

4. Wrapper script: Use pkgs.writeShellScriptBin

Optional Enhancements

• Shell alias (s or ssh → kitten ssh)
• Integration with kitty's ssh.conf for per-host settings

Related

• Part of XDG default apps infrastructure (modules/system76/default-apps.nix)
• Similar pattern to browser/terminal defaults