debug: synology_sender에 전송 내용 로그 추가

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

nanoclaude/services/synology_sender.py

@@ -40,6 +40,7 @@ async def send_to_synology(text: str, *, raw: bool = False) -> bool:
                 data={"payload": payload},
             )
             if resp.status_code == 200:
+                logger.info("Synology sent (%d chars): %s", len(text), text[:100])
                 return True
             logger.error("Synology send failed: %d %s", resp.status_code, resp.text)
             return False