fix(gateway): drop text snippet from debounce debug log (CodeQL)

CodeQL py/clear-text-logging-sensitive-data flagged the candidate-accept
debug log including event.text[:60]. Log text_len instead — sufficient for
debugging burst behavior without surfacing message contents.

Co-authored-by: Paulo Nascimento <pnascimento9596@gmail.com>

gateway/platforms/base.py

@@ -2773,10 +2773,10 @@ class BasePlatformAdapter(ABC):
         )
         if result:
             logger.debug(
-                "[%s] Queue-text debounce candidate accepted: session=%s text=%.60s",
+                "[%s] Queue-text debounce candidate accepted: session=%s text_len=%d",
                 self.name,
                 getattr(event, "session_key", "?"),
-                (event.text or "")[:60],
+                len(event.text or ""),
             )
         return result