feat(purchase): 구매 취소/반품 + 입고일 기준 월별 분석

- 상태 추가: cancelled(구매취소), returned(반품)
- API: PUT /:id/cancel, /:id/return, /:id/revert-cancel
- 데스크탑: 구매완료→취소 버튼, 입고완료→반품 버튼, 취소→되돌리기
- 분석 페이지: 구매일/입고일 기준 전환 토글, 입고일 기준 월간 분류 집계 + 입고 목록
- Settlement API: GET /received-summary, /received-list (입고일 기준)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

system1-factory/api/models/settlementModel.js

@@ -83,6 +83,47 @@ const SettlementModel = {
     return { year_month: yearMonth, vendor_id: vendorId, status: 'pending' };
   },
 
+  // 입고일 기준 월간 분류별 요약
+  async getCategorySummaryByReceived(yearMonth) {
+    const db = await getDb();
+    const [rows] = await db.query(`
+      SELECT ci.category,
+             COUNT(*) AS count,
+             SUM(pr.quantity * COALESCE(p.unit_price, 0)) AS total_amount
+      FROM purchase_requests pr
+      LEFT JOIN consumable_items ci ON pr.item_id = ci.item_id
+      LEFT JOIN purchases p ON p.request_id = pr.request_id
+      WHERE pr.status = 'received'
+        AND DATE_FORMAT(pr.received_at, '%Y-%m') = ?
+      GROUP BY ci.category
+    `, [yearMonth]);
+    return rows;
+  },
+
+  // 입고일 기준 월간 상세 목록
+  async getMonthlyReceived(yearMonth) {
+    const db = await getDb();
+    const [rows] = await db.query(`
+      SELECT pr.request_id, pr.quantity, pr.received_at, pr.received_location,
+             pr.received_photo_path, pr.status, pr.notes,
+             ci.item_name, ci.spec, ci.maker, ci.category, ci.unit, ci.base_price,
+             p.unit_price, p.purchase_date, p.vendor_id,
+             v.vendor_name,
+             su.name AS requester_name,
+             rsu.name AS received_by_name
+      FROM purchase_requests pr
+      LEFT JOIN consumable_items ci ON pr.item_id = ci.item_id
+      LEFT JOIN purchases p ON p.request_id = pr.request_id
+      LEFT JOIN vendors v ON p.vendor_id = v.vendor_id
+      LEFT JOIN sso_users su ON pr.requester_id = su.user_id
+      LEFT JOIN sso_users rsu ON pr.received_by = rsu.user_id
+      WHERE pr.status IN ('received', 'returned')
+        AND DATE_FORMAT(pr.received_at, '%Y-%m') = ?
+      ORDER BY pr.received_at DESC
+    `, [yearMonth]);
+    return rows;
+  },
+
   // 가격 변동 목록 (월간)
   async getPriceChanges(yearMonth) {
     const db = await getDb();