style(malaysia): 입출고 엑셀 헤더 서식 + 열너비 자동

- A1~C1 파랑 배경/흰색 굵은글씨/가운데 정렬
- A~C 열너비 내용 길이 자동(한글 폭 2배 보정, 8~50 clamp)

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

app/modules/malaysia/router.py

@@ -335,11 +335,14 @@ async def movements_export(request: Request) -> StreamingResponse:
     item_names = st.item_name_map()
 
     from openpyxl import Workbook  # noqa: WPS433
+    from openpyxl.styles import Alignment, Font, PatternFill  # noqa: WPS433
+    from openpyxl.utils import get_column_letter  # noqa: WPS433
 
     wb = Workbook()
     ws = wb.active
     ws.title = f"{mtype}_{mdate}"
-    ws.append(["사방넷코드", "수량", "이름"])
+    header = ["사방넷코드", "수량", "이름"]
+    ws.append(header)
     for code in sorted(totals.keys()):
         qty = totals[code]
         if qty == 0:
@@ -350,6 +353,26 @@ async def movements_export(request: Request) -> StreamingResponse:
             names.get(code) or item_names.get(code) or code,
         ])
 
+    # 제목행(A1~C1): 파랑 배경 + 흰색 굵은글씨 + 가운데 정렬
+    fill = PatternFill(start_color="FF4472C4", end_color="FF4472C4", fill_type="solid")
+    font = Font(color="FFFFFFFF", bold=True)
+    center = Alignment(horizontal="center", vertical="center")
+    for col in range(1, len(header) + 1):
+        cell = ws.cell(row=1, column=col)
+        cell.fill = fill
+        cell.font = font
+        cell.alignment = center
+
+    # 열너비 자동(내용 길이 기준, 한글 폭 보정). 최소 8 ~ 최대 50.
+    for col in range(1, len(header) + 1):
+        letter = get_column_letter(col)
+        longest = 0
+        for cell in ws[letter]:
+            v = "" if cell.value is None else str(cell.value)
+            width = sum(2 if ord(ch) > 0x1100 else 1 for ch in v)
+            longest = max(longest, width)
+        ws.column_dimensions[letter].width = max(8, min(50, longest + 2))
+
     buf = io.BytesIO()
     wb.save(buf)
     buf.seek(0)