fix(gateway): keep no-patterns early return in mention compilation

The compile_mention_patterns promotion moved the 'patterns is None ->
return []' short-circuit into the shared helper, which meant the
telegram/dingtalk wrappers now evaluated self.name (via log_prefix=)
even on the no-patterns path. On main that path returned before
touching any adapter attributes; tests construct bare adapters via
object.__new__ that lack .platform, so TestTelegramGuestMentionGating
failed with AttributeError. Restore the early return in both wrappers
for exact behavior parity with main.

plugins/platforms/dingtalk/adapter.py

@@ -458,6 +458,12 @@ class DingTalkAdapter(BasePlatformAdapter):
                         loaded = [part.strip() for part in raw.split(",") if part.strip()]
                 patterns = loaded
 
+        if patterns is None:
+            # Parity with the historical inline implementation: return before
+            # evaluating ``self.name`` (avoids touching adapter attributes on
+            # the no-patterns path).
+            return []
+
         return compile_mention_patterns(
             patterns,
             log_prefix=self.name,

plugins/platforms/telegram/adapter.py

@@ -7818,6 +7818,12 @@ class TelegramAdapter(BasePlatformAdapter):
                         loaded = [part.strip() for part in raw.split(",") if part.strip()]
                 patterns = loaded
 
+        if patterns is None:
+            # Parity with the historical inline implementation: return before
+            # evaluating ``self.name`` (tests construct bare adapters via
+            # object.__new__ that lack the attributes ``name`` reads).
+            return []
+
         return compile_mention_patterns(
             patterns,
             log_prefix=self.name,