feat(matrix): add adapter baseline and platform-aware command hints

core/handlers/message.py

@@ -4,9 +4,18 @@ from __future__ import annotations
 from core.protocol import IncomingMessage, OutgoingMessage, OutgoingTyping
 
 
+def _start_command(platform: str) -> str:
+    return "!start" if platform == "matrix" else "/start"
+
+
 async def handle_message(event: IncomingMessage, auth_mgr, platform, chat_mgr, settings_mgr) -> list:
     if not await auth_mgr.is_authenticated(event.user_id):
-        return [OutgoingMessage(chat_id=event.chat_id, text="Введите /start чтобы начать.")]
+        return [
+            OutgoingMessage(
+                chat_id=event.chat_id,
+                text=f"Введите {_start_command(event.platform)} чтобы начать.",
+            )
+        ]
 
     # Voice slot fallback: audio attachment without registered voice_handler
     if event.attachments and event.attachments[0].type == "audio":