fix(kratos): make Android Mosh app work with nushell login shell

The old Android Mosh app discovers mosh-server via POSIX shell idioms
(command -v / type) through the user's login shell. Nushell has no
command/type builtins and which prints a table, so the app reported
'mosh-server Not Found' on kratos (user shell: nu) while working on
hermes (app logs in as bash user).

Fix: use bash as login shell on kratos and exec into nushell for
interactive login sessions via programs.bash.interactiveShellInit.
Non-interactive SSH exec (app bootstrap, Termux mosh) stays in bash
where POSIX semantics work.

Also fixes the stale nh flake path (p/nixos -> p/NIX).

hosts/m3-kratos/configuration.nix

@@ -70,6 +70,12 @@
 
   # Define a user account. Don't forget to set a password with ‘passwd’.
 
+  # bash as login shell wrapper: non-interactive SSH clients (e.g. the
+  # Android Mosh app bootstrap, which runs `command -v mosh-server`)
+  # need POSIX shell semantics. Interactive login sessions exec into
+  # nushell automatically — see programs.bash in ./programs.nix.
+  users.users.m3tam3re.shell = pkgs.bashInteractive;
+
   # List packages installed in system profile. To search, run:
   # $ nix search wget
   environment.systemPackages = with pkgs; [neovim git];