feat: remove tmux from dev and add claude resume shortcut

hosts/dev/configuration.nix

@@ -55,13 +55,18 @@ in
   programs.zsh.enable = true;
   users.defaultUserShell = pkgs.zsh;
 
-  # Auto-attach to tmux on SSH login
-  environment.interactiveShellInit = ''
-    if [[ -n "$SSH_CONNECTION" ]] && [[ -z "$TMUX" ]]; then
-      tmux attach-session -t main 2>/dev/null || tmux new-session -s main
-    fi
+  # Welcome message with Claude Code reminder
+  users.motd = ''
+    Welcome to dev
+
+    Claude Code: claude or cr (resume last session)
   '';
 
+  # Short alias for resuming Claude sessions
+  programs.zsh.shellAliases = {
+    cr = "claude --resume";
+  };
+
   # Passwordless sudo for dominik
   security.sudo.extraRules = [{
     users = [ "dominik" ];