feat: P10(#3) 환수 보험사자료 업로드 — 보험사 통보 기반 chargeback 인입 (PL 자율진행)

incar '환수보험사자료 업로드' 대응. GA는 LAPSE 계약 기반 자동환수만 있고 보험사가
통보한 환수자료(증권번호+환수금액)를 직접 인입하는 경로가 없던 갭. 신규 테이블 없이
기존 chargeback(V6) 재사용.

- DB(V113): 메뉴 CHARGEBACK_DATA(환수자료관리, GRP_SETTLE, /settle/chargeback-data)
  + 권한 READ/CREATE/EXPORT + 역할부여.
- core: ChargebackUploadExcelVO(@ExcelColumn 증권번호/환수금액/실효월/환수율) +
  ChargebackResp/SearchParam + ChargebackMapper.selectList/countByCondition/
  existsByContractAndMonth + ContractMapper.selectByPolicyNo(contract_date 포함).
- api: ChargebackUploadService.upload(settleMonth,file) — ExcelService.importLargeExcel
  로 SAX 파싱, policy_no→contract/agent 해소(미존재=에러행), 중복(contract+월) skip,
  실효월 YYYYMM→경과월 변환(ChronoUnit), ChargebackVO status=NEW·remain=cb_amount
  insertBatch. ChargebackService.list/export. ChargebackController(/api/chargebacks
  /upload, GET 목록, export).
- frontend: ChargebackData 화면(정산월+파일 업로드, 결과 성공/스킵/에러행 표시, AG Grid
  목록 합계행, 엑셀) + api/chargeback.ts + App 라우트.

검증: build SUCCESSFUL, Flyway V113(schema v113). 라이브 업로드 e2e — 정상 2건 INSERT
(NEW, remain=cb_amount) + 미존재 증권번호 1건 에러행 리포트 + 중복 skip, GET 목록 200,
경과월 변환 동작 확인. 테스트 chargeback 전건 정리. 스펙 docs/DOMAIN_GAP_P10.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

ga-frontend/src/api/chargeback.ts

@@ -0,0 +1,62 @@
+import api, { PageResponse, unwrap } from './request';
+
+// ── Types ──────────────────────────────────────────
+
+export type ChargebackStatus = 'NEW' | 'PROCESSING' | 'SETTLED' | 'CANCELLED';
+
+export interface ChargebackRow extends Record<string, unknown> {
+  cbId: number;
+  policyNo: string;
+  agentId: number;
+  agentName: string;
+  contractorName: string;
+  lapseMonth: number | null;
+  cbRate: number | null;
+  cbAmount: number;
+  paidAmount: number;
+  remainAmount: number;
+  settleMonth: string;
+  status: ChargebackStatus;
+  createdAt: string;
+}
+
+export interface ChargebackSearchParam {
+  settleMonth?: string;
+  agentId?: number;
+  status?: string;
+  policyNo?: string;
+  pageNum?: number;
+  pageSize?: number;
+}
+
+export interface ChargebackUploadResult {
+  successCount: number;
+  errorCount: number;
+  skipCount: number;
+  errors: Array<{ rowNo: number; reason: string }>;
+}
+
+// ── API ───────────────────────────────────────────
+
+export const chargebackApi = {
+  list: (p: ChargebackSearchParam) =>
+    unwrap<PageResponse<ChargebackRow>>(
+      api.get('/api/chargebacks', { params: p }),
+    ),
+
+  upload: (settleMonth: string, file: File) => {
+    const form = new FormData();
+    form.append('file', file);
+    return unwrap<ChargebackUploadResult>(
+      api.post(`/api/chargebacks/upload?settleMonth=${settleMonth}`, form, {
+        headers: { 'Content-Type': 'multipart/form-data' },
+      }),
+    );
+  },
+
+  export: (p: ChargebackSearchParam) =>
+    api.get('/api/chargebacks/export', {
+      params: p,
+      responseType: 'blob',
+    }),
+};