feat(drug-usage): 단위 마스터 + 총사용량 표시 + 순차 API 호출

- drug_unit.py: SUNG_CODE 기반 단위 판별 함수 추가
- 조제 상세에 총사용량 + 단위 표시 (예: 1,230정)
- API 순차 호출로 DB 세션 충돌 방지

backend/app.py

@@ -8905,6 +8905,8 @@ def api_drug_usage_imports(drug_code):
 @app.route('/api/drug-usage/<drug_code>/prescriptions')
 def api_drug_usage_prescriptions(drug_code):
     """약품별 조제(매출) 상세 API"""
+    from utils.drug_unit import get_drug_unit
+    
     start_date = request.args.get('start_date', '')
     end_date = request.args.get('end_date', '')
     
@@ -8913,6 +8915,16 @@ def api_drug_usage_prescriptions(drug_code):
     
     try:
         pres_session = db_manager.get_session('PM_PRES')
+        drug_session = db_manager.get_session('PM_DRUG')
+        
+        # 약품 정보 조회 (단위 판별용)
+        drug_info = drug_session.execute(text("""
+            SELECT GoodsName, SUNG_CODE FROM CD_GOODS WHERE DrugCode = :drug_code
+        """), {'drug_code': drug_code}).fetchone()
+        
+        goods_name = drug_info.GoodsName if drug_info else ''
+        sung_code = drug_info.SUNG_CODE if drug_info else ''
+        unit = get_drug_unit(goods_name, sung_code)
         
         result = pres_session.execute(text("""
             SELECT 
@@ -8934,12 +8946,15 @@ def api_drug_usage_prescriptions(drug_code):
         items = []
         seen_patients = set()
         recent_patients = []  # 최근 조제받은 환자 (중복 제외, 최대 3명)
+        total_usage = 0  # 총 사용량
         
         for row in result:
             dosage = float(row.dosage) if row.dosage else 0
             freq = float(row.frequency) if row.frequency else 0
             days = int(row.days) if row.days else 0
             patient = row.patient_name or ''
+            qty = dosage * freq * days
+            total_usage += qty
             
             # 중복 제외 환자 목록 (최근순, 최대 3명)
             if patient and patient not in seen_patients:
@@ -8955,7 +8970,7 @@ def api_drug_usage_prescriptions(drug_code):
                 'dosage': dosage,
                 'frequency': freq,
                 'days': days,
-                'total_qty': dosage * freq * days
+                'total_qty': qty
             })
         
         return jsonify({
@@ -8964,6 +8979,8 @@ def api_drug_usage_prescriptions(drug_code):
             'total_count': len(items),
             'unique_patients': len(seen_patients),
             'recent_patients': recent_patients,
+            'total_usage': total_usage,
+            'unit': unit,
             'items': items
         })
     except Exception as e: