fix(gateway): guard adapter-trust check against bare GatewayRunner in tests

_adapter_enforces_own_access_policy accessed self.adapters directly, but
several auth tests build a bare GatewayRunner via object.__new__ without
setting .adapters (pitfalls.md #17). Read it defensively with getattr so a
missing/empty adapter map means "no adapter owns the policy" instead of
raising AttributeError.

Fixes 4 tests: test_feishu_bot_auth_bypass, test_discord_bot_auth_bypass (x2),
test_signal::test_signal_in_allowlist_maps.

gateway/run.py

@@ -6556,7 +6556,13 @@ class GatewayRunner:
         """
         if not platform:
             return False
-        adapter = self.adapters.get(platform)
+        # Some test helpers build a bare GatewayRunner via object.__new__ and
+        # never set ``adapters``; treat a missing/empty map as "no adapter"
+        # rather than raising (see pitfalls.md #17).
+        adapters = getattr(self, "adapters", None)
+        if not adapters:
+            return False
+        adapter = adapters.get(platform)
         if adapter is None:
             return False
         return bool(getattr(adapter, "enforces_own_access_policy", False))