fix(s6): register profile gateways without auto-starting (#46266)

* fix(s6): prevent profile create from auto-starting gateway service

When hermes profile create runs inside an s6 container,
_maybe_register_gateway_service() calls register_profile_gateway()
which creates the service directory and triggers s6-svscanctl -a.
Previously the service always started immediately, causing profiles
that share the main gateway's bot token (e.g. Kanban worker profiles)
to fail with a token-lock conflict and persist gateway_state: running
— becoming zombies that resurrect on every container restart.

Wire the existing start_now parameter through the S6 implementation:
when start_now=False, write a  marker file (same pattern as
container_boot.py _register_gateway_slot) so s6-supervise leaves the
service stopped until the user explicitly runs hermes -p <profile>
gateway start.

4 files, +61/-6, 4 new tests (all passing).

* test(docker): wait for gateway running state before restart

---------

Co-authored-by: liuhao1024 <sunsky.lau@gmail.com>

tests/docker/test_container_restart.py

@@ -296,7 +296,8 @@ def test_live_gateway_autostarts_after_real_restart_without_manual_state_stamp(
         )
         if r.returncode == 0 and '"gateway_state"' in r.stdout:
             state = r.stdout
-            break
+            if '"running"' in state:
+                break
         time.sleep(0.5)
     assert '"running"' in state, (
         f"gateway never persisted running state pre-restart: {state!r}"