fix(scheduler): 修復 Gunicorn 4 workers 重複發送排程通知

根因：APScheduler 在 openclaw_bot_routes.py 透過 record_once 啟動，
但 record_once 只防止同一 process 內重複；Gunicorn --workers 4 有
4 個獨立 worker process，各自啟動一個 scheduler，導致早報/晚報/Excel
每次觸發都送出 4 份。

修復：start_scheduler() 改用 fcntl.LOCK_EX|LOCK_NB 搶佔 /tmp/openclaw_scheduler.lock，
只有搶到鎖的 worker 啟動排程，其餘 3 個 worker 靜默跳過。

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

routes/openclaw_bot_routes.py

@@ -3300,9 +3300,32 @@ def send_daily_excel():
         sys_log.error(f"[AutoExcel] {e}")
 
 
+_sched_lock_fh = None  # 持有鎖的 file handle，進程退出時自動釋放
+
+
 def start_scheduler():
-    """啟動排程（Flask app 啟動後呼叫）"""
-    global _scheduler
+    """啟動排程（Flask app 啟動後呼叫）
+    使用 fcntl exclusive lock 確保 Gunicorn 多 worker 環境下只有一個 worker 運行排程。
+    """
+    global _scheduler, _sched_lock_fh
+    import fcntl, atexit
+
+    lock_path = '/tmp/openclaw_scheduler.lock'
+    try:
+        _sched_lock_fh = open(lock_path, 'w')
+        fcntl.flock(_sched_lock_fh.fileno(), fcntl.LOCK_EX | fcntl.LOCK_NB)
+    except OSError:
+        sys_log.info("[OpenClawBot] Scheduler lock busy — another worker owns it, skipping")
+        return
+
+    @atexit.register
+    def _release_sched_lock():
+        try:
+            fcntl.flock(_sched_lock_fh.fileno(), fcntl.LOCK_UN)
+            _sched_lock_fh.close()
+        except Exception:
+            pass
+
     try:
         from apscheduler.schedulers.background import BackgroundScheduler
         from apscheduler.triggers.cron import CronTrigger
@@ -3315,7 +3338,7 @@ def start_scheduler():
         _scheduler.add_job(send_weekly_report,     CronTrigger(day_of_week='mon', hour=9, minute=0))
         _scheduler.add_job(check_anomalies,        CronTrigger(hour='9,12,15,18', minute=0))
         _scheduler.start()
-        sys_log.info("[OpenClawBot] Scheduler started ✓ (competitor/morning/excel/evening/weekly/anomaly)")
+        sys_log.info("[OpenClawBot] Scheduler started ✓ pid=%d (competitor/morning/excel/evening/weekly/anomaly)", os.getpid())
     except ImportError:
         sys_log.warning("[OpenClawBot] APScheduler 未安裝 — 排程功能停用")
     except Exception as e: