fix(setup): drop post-setup chat handoff (#25067)

Removes the 'Launch hermes chat now? (Y/n)' prompt at the end of
hermes setup. The summary already prints 'Ready to go! → hermes'
so the auto-launch was redundant, and on macOS 26+ it could crash
in prompt_toolkit when setup was invoked from the curl install
script with stdin redirected from /dev/tty (#5884, #6128).

After setup, users run 'hermes' themselves like every other CLI
tool. Same pattern applies to the Windows installer.

Closes #6128 (narrower env-var-guarded fix superseded by removing
the prompt outright).

tests/hermes_cli/test_setup_reconfigure.py

@@ -63,7 +63,6 @@ def _enter_existing_install_patches(stack, **extra):
         ("hermes_cli.setup.get_env_value", {"return_value": None}),
         ("hermes_cli.auth.get_active_provider", {"return_value": "openrouter"}),
         ("hermes_cli.setup._print_setup_summary", {}),
-        ("hermes_cli.setup._offer_launch_chat", {}),
         ("hermes_cli.setup._offer_openclaw_migration", {"return_value": False}),
     ]:
         stack.enter_context(patch(target, **kwargs))