fix(gateway): route --all stop/restart through s6 under container

PR #30136 review caught that `hermes gateway stop --all` and
`... restart --all` were broken under s6. The Phase 4 dispatcher was
gated on `not stop_all` (and the symmetric restart_all), so `--all`
fell through to `kill_gateway_processes(all_profiles=True)`. pkill
SIGTERMed every gateway, s6-supervise observed the crashes, and
restarted every gateway ~1s later — net effect: `--all` *kicked*
gateways instead of *stopping* them.

Add `_dispatch_all_via_service_manager_if_s6(action)` that iterates
`mgr.list_profile_gateways()` and routes stop/restart through each
service slot. s6's `want up`/`want down` flips correctly, so a
stop persists. Partial failures are surfaced per-profile with a
running success count; the host pkill path is only reached when s6
isn't in play.

`start --all` isn't a CLI surface — the helper rejects it and
returns False (host code path can take over).

hermes_cli/gateway.py

@@ -5066,6 +5066,57 @@ def _dispatch_via_service_manager_if_s6(
     return True
 
 
+def _dispatch_all_via_service_manager_if_s6(action: str) -> bool:
+    """Inside a container with s6, dispatch ``--all`` lifecycle to every
+    registered profile gateway.
+
+    Returns True iff dispatched (caller should ``return``); False
+    otherwise — caller continues with the host-side code path.
+
+    Without this, ``hermes gateway stop --all`` and ``... restart --all``
+    fall through to ``kill_gateway_processes(all_profiles=True)``, which
+    just ``pkill``s every gateway process. s6-supervise observes the
+    crash and restarts each one ~1s later — so ``--all`` ends up
+    *kicking* every gateway instead of *stopping* it. By iterating
+    ``list_profile_gateways()`` and sending the lifecycle command
+    through the service manager we get the intended semantics (s6's
+    ``want up``/``want down`` flips correctly so supervise stays down
+    after a stop).
+
+    ``action`` is one of ``stop`` / ``restart`` (``start --all`` isn't
+    a supported CLI surface).
+    """
+    from hermes_cli.service_manager import (
+        detect_service_manager,
+        get_service_manager,
+    )
+
+    if detect_service_manager() != "s6":
+        return False
+    if action not in ("stop", "restart"):
+        return False
+    mgr = get_service_manager()
+    profiles = mgr.list_profile_gateways()
+    if not profiles:
+        print("✗ No profile gateways registered under s6")
+        return True
+    fn = mgr.stop if action == "stop" else mgr.restart
+    errors: list[tuple[str, Exception]] = []
+    for profile in profiles:
+        service_name = f"gateway-{profile}"
+        try:
+            fn(service_name)
+        except Exception as exc:  # noqa: BLE001 — report and continue
+            errors.append((profile, exc))
+    succeeded = len(profiles) - len(errors)
+    verb = "stopped" if action == "stop" else "restarted"
+    if succeeded:
+        print(f"✓ {verb.capitalize()} {succeeded} profile gateway(s) under s6")
+    for profile, exc in errors:
+        print(f"✗ Could not {action} gateway-{profile}: {exc}")
+    return True
+
+
 def gateway_command(args):
     """Handle gateway subcommands."""
     try:
@@ -5275,7 +5326,11 @@ def _gateway_command_inner(args):
         system = getattr(args, 'system', False)
 
         # Phase 4: inside a container with s6, dispatch via the service
-        # manager. `--all` is left to the existing process-sweep path below.
+        # manager. ``--all`` iterates every registered profile gateway
+        # through s6 (otherwise it would fall through to ``pkill``,
+        # which s6-supervise observes as a crash and immediately restarts).
+        if stop_all and _dispatch_all_via_service_manager_if_s6("stop"):
+            return
         if not stop_all and _dispatch_via_service_manager_if_s6("stop"):
             return
 
@@ -5349,7 +5404,12 @@ def _gateway_command_inner(args):
         service_configured = False
 
         # Phase 4: inside a container with s6, dispatch via the service
-        # manager (s6-svc -t restarts the supervised process).
+        # manager (s6-svc -t restarts the supervised process). ``--all``
+        # iterates every registered profile gateway through s6; without
+        # this it would fall through to ``pkill``, which s6-supervise
+        # would observe as a crash and immediately restart anyway.
+        if restart_all and _dispatch_all_via_service_manager_if_s6("restart"):
+            return
         if not restart_all and _dispatch_via_service_manager_if_s6("restart"):
             return