refactor(gateway-cli): dispatch-table subcommands and shared service helpers in hermes_cli/gateway.py

hermes_cli/gateway.py (9178 -> 6906):
- `hermes gateway` subcommand routing: if/elif chain -> _GATEWAY_SUBCOMMANDS dispatch table of
  _cmd_* handlers; _stop_installed_service and _refuse_from_inside_gateway unify the
  stop/restart/uninstall service-stop and self-target guards.
- One systemd unit template; _systemctl_show, systemctl reset+action, is-active probes,
  _installed_service_kind ladder (3 sites), launchctl-list PID probe, launchd bootstrap+kickstart
  helper, legacy-unit removal loop, loop-tick witness ping, ps/wmic line parsers, planned-stop
  marker helper, _CAPTURE_TEXT subprocess kwargs (21 sites), _gw_windows() accessor (15 lazy
  imports).
- run_gateway startup helpers, reaper exclusion set, Windows process listing extracted; wizard
  service actions and platform-setup prompts unified (_setup_service_action).
- Dead: _windows_scheduled_task_running (test-only), _container_systemd_operational (inlined),
  whatsapp/email/matrix built-in status branches (those platforms are registry plugins).
- try/except-pass around single statements -> contextlib.suppress; comments/docstrings compacted
  to the WHY (bounded_probe_run vs subprocess.run on Windows, pythonw launcher-stub filtering,
  raw-record vs validated-probe exclusion in the orphan reaper, Scheduled-Task Ready-vs-Running).
- `hermes gateway --help` byte-identical.

tests/hermes_cli/test_gateway.py

@@ -1,9 +1,7 @@
 """Tests for hermes_cli.gateway."""
 
-import argparse
 import json
 import os
-import signal
 import subprocess
 import sys
 import textwrap
@@ -1089,7 +1087,6 @@ class TestWindowsScheduledTaskSupervisorGuard:
             raise AssertionError("subprocess must not run off Windows")
 
         monkeypatch.setattr(gateway.subprocess, "run", _boom_run)
-        assert gateway._windows_scheduled_task_running("HermesGateway") is False
         assert gateway._windows_scheduled_task_supervises("HermesGateway") is False
         assert gateway._windows_scheduled_task_state("HermesGateway") is None
 
@@ -1100,7 +1097,6 @@ class TestWindowsScheduledTaskSupervisorGuard:
         for state, expected in states.items():
             monkeypatch.setattr(gateway, "_windows_scheduled_task_state", lambda name, s=state: s)
             assert gateway._windows_scheduled_task_supervises("Hermes_Gateway") is expected, state
-            assert gateway._windows_scheduled_task_running("Hermes_Gateway") is (state == "Running")
 
 
 def test_find_windows_gateway_services_maps_verified_pid_tree(monkeypatch):