fix(gateway): include QQBOT in allowlist-aware unauthorized DM map

Follow-up to #9337: _is_user_authorized maps Platform.QQBOT to
QQ_ALLOWED_USERS, but the new platform_env_map inside
_get_unauthorized_dm_behavior omitted it.  A QQ operator with a strict
user allowlist would therefore still have the gateway send pairing
codes to strangers.

Adds QQBOT to the env map and a regression test.

gateway/run.py

@@ -2988,6 +2988,7 @@ class GatewayRunner:
                 Platform.WECOM_CALLBACK: "WECOM_CALLBACK_ALLOWED_USERS",
                 Platform.WEIXIN:   "WEIXIN_ALLOWED_USERS",
                 Platform.BLUEBUBBLES: "BLUEBUBBLES_ALLOWED_USERS",
+                Platform.QQBOT:    "QQ_ALLOWED_USERS",
             }
             if os.getenv(platform_env_map.get(platform, ""), "").strip():
                 return "ignore"