fix: resolve out-of-range date error (31 days) in monthly stats calculation

crawler/daily_summary.py

@@ -139,10 +139,14 @@ def calculate_monthly_stats(target_month: str):
         
         for pid in plant_ids:
             # 2. 해당 월의 Daily 합계 조회
+            import calendar
+            year_str, month_str = target_month.split("-")
+            last_day = calendar.monthrange(int(year_str), int(month_str))[1]
+            
             d_res = client.table("daily_stats").select("total_generation") \
                 .eq("plant_id", pid) \
                 .gte("date", f"{target_month}-01") \
-                .lte("date", f"{target_month}-31") \
+                .lte("date", f"{target_month}-{last_day:02d}") \
                 .execute()
             
             if not d_res.data: