feat(returns): v8.59 반품 입고 중복 경고 및 송장 공백 매칭 개선

- 반품 입고 시 이미 등록된 송장번호면 중복 경고 안내창 표시
- 송장번호 입력값 strip 및 조회 쿼리 TRIM 적용으로 공백 매칭 문제 해결

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

routers/returns.py

@@ -90,6 +90,7 @@ async def return_lookup(tracking_no: str):
 @router.post("/request")
 async def create_return_request(req: ReturnRequest):
     try:
+        req.tracking_no = req.tracking_no.strip()
         conn = get_return_db_conn()
         cur = conn.cursor()
         if req.id:
@@ -117,7 +118,7 @@ async def get_return_requests(tracking_no: Optional[str] = None):
         conn = get_return_db_conn()
         cur = conn.cursor()
         if tracking_no:
-            cur.execute("SELECT * FROM return_requests WHERE tracking_no = %s ORDER BY created_at DESC LIMIT 1", (tracking_no,))
+            cur.execute("SELECT * FROM return_requests WHERE TRIM(tracking_no) = %s ORDER BY created_at DESC LIMIT 1", (tracking_no.strip(),))
         else:
             cur.execute("SELECT * FROM return_requests ORDER BY id DESC LIMIT 50")
         rows = cur.fetchall()
@@ -151,7 +152,7 @@ async def create_return_receive_bulk(req: BulkReturnReceive):
             address = ""
             
             # 1. Check return_requests
-            cur_return.execute("SELECT mall, receiver_name, phone, address, request_type, remarks FROM return_requests WHERE tracking_no = %s", (tracking_no,))
+            cur_return.execute("SELECT mall, receiver_name, phone, address, request_type, remarks FROM return_requests WHERE TRIM(tracking_no) = %s", (tracking_no,))
             req_row = cur_return.fetchone()
             if req_row:
                 mall = req_row['mall'] or ""
@@ -203,11 +204,35 @@ async def create_return_receive_bulk(req: BulkReturnReceive):
 @router.post("/receive")
 async def create_return_receive(req: ReturnReceive):
     try:
+        req.tracking_no = req.tracking_no.strip()
         conn = get_return_db_conn()
         cur = conn.cursor()
-        
+
+        # 중복 송장 검사
+        if req.id:
+            cur.execute("""
+                SELECT receive_date, receiver_name, phone, mall, receive_status, remarks
+                FROM return_receivings
+                WHERE TRIM(tracking_no) = %s AND id != %s
+            """, (req.tracking_no, req.id))
+        else:
+            cur.execute("""
+                SELECT receive_date, receiver_name, phone, mall, receive_status, remarks
+                FROM return_receivings
+                WHERE TRIM(tracking_no) = %s
+            """, (req.tracking_no,))
+
+        dup = cur.fetchone()
+        if dup:
+            conn.close()
+            return {
+                "success": False,
+                "error_type": "duplicate",
+                "data": dict(dup)
+            }
+
         if not req.id:
-            cur.execute("SELECT request_type, remarks FROM return_requests WHERE tracking_no = %s", (req.tracking_no,))
+            cur.execute("SELECT request_type, remarks FROM return_requests WHERE TRIM(tracking_no) = %s", (req.tracking_no,))
             req_row = cur.fetchone()
             if not req_row:
                 if req.remarks: