fix(gateway): coerce plaintext "restart gateway" DMs to /restart

Narrow plaintext shortcut that rewrites a tiny set of admin phrases
("restart gateway", "restart the gateway", "restart hermes") into the
/restart slash command, but only in DMs. Scope is intentionally tight:

- DM text messages only — group chats keep natural-language semantics
- Exact restart-style phrases only
- Skips anything already starting with "/"

Without this, the LLM can receive "restart gateway" as a user turn and
try to satisfy it via the terminal tool (systemctl restart ...). That
kills the gateway while the originating agent is still running, which
leaves systemd in "draining" state waiting on a process it's about to
kill. Routing the phrase to the slash-command dispatcher bypasses the
agent loop and uses the existing restart machinery (request_restart).

Called once, at the adapter level in BasePlatformAdapter.handle_message,
so every platform gets it for free and pending-message reinjection is
covered by the same call site.

Adds 2 Telegram-parametrized e2e tests: DM routes to request_restart,
group chats fall through to the normal agent path.

gateway/platforms/base.py

@@ -907,6 +907,41 @@ class MessageEvent:
         return args
 
 
+_PLAINTEXT_GATEWAY_RESTART_PATTERNS: tuple[re.Pattern[str], ...] = (
+    re.compile(r"^(?:please\s+)?restart\s+(?:the\s+)?gateway[.!?\s]*$", re.IGNORECASE),
+    re.compile(r"^(?:please\s+)?restart\s+(?:the\s+)?hermes\s+gateway[.!?\s]*$", re.IGNORECASE),
+    re.compile(r"^(?:please\s+)?restart\s+hermes[.!?\s]*$", re.IGNORECASE),
+)
+
+
+def coerce_plaintext_gateway_command(event: "MessageEvent") -> None:
+    """Rewrite a tiny set of DM plaintext admin phrases into slash commands.
+
+    This keeps high-impact operational phrases like ``restart gateway`` out of
+    the LLM/tool path, where they can trigger a self-restart from inside the
+    currently running agent and leave the gateway stuck in ``draining`` while it
+    waits for that same agent to finish.
+
+    Scope is intentionally narrow: DM text messages only, exact restart-style
+    phrases only. Group chats keep natural-language semantics.
+    """
+    try:
+        if event is None or event.message_type != MessageType.TEXT:
+            return
+        text = (event.text or "").strip()
+        if not text or text.startswith("/"):
+            return
+        source = getattr(event, "source", None)
+        if getattr(source, "chat_type", None) != "dm":
+            return
+        for pattern in _PLAINTEXT_GATEWAY_RESTART_PATTERNS:
+            if pattern.match(text):
+                event.text = "/restart"
+                return
+    except Exception:
+        return
+
+
 @dataclass 
 class SendResult:
     """Result of sending a message."""
@@ -2193,6 +2228,8 @@ class BasePlatformAdapter(ABC):
         """
         if not self._message_handler:
             return
+
+        coerce_plaintext_gateway_command(event)
         
         session_key = build_session_key(
             event.source,