fix(cash): vouchers-json batch改为纯内容指纹(不含时间戳) — 快照每10分钟重推必须幂等命中

- batch=zxt-{sha1前10}，同内容任意时刻重推 → 同一batch → already_imported跳过
- 原带秒级时间戳导致指纹去重失效(靠行级防重兜底,但会产生噪音import_logs)
- 验收脚本补用例4b(三次重发batch不变+already_imported), 13/13 PASS

backend/scripts/verify_zxt_vouchers_json.py

@@ -94,6 +94,13 @@ r4 = client.post("/api/cma/cash/import/vouchers-json", json=payload, headers=HDR
 j4 = r4.json()
 results.append(check("用例4 同指纹重复导入 already_imported", r4.status_code == 200 and j4.get("already_imported") is True, f"body={r4.text[:200]}"))
 
+# ── 用例4b: 同内容不同「模拟时间」仍同 batch → 幂等（batch 不含时间戳）──
+def j4b_is_already(resp, j4):
+    j = resp.json()
+    return j.get("already_imported") is True and j.get("batch") == j4.get("batch")
+r4b = client.post("/api/cma/cash/import/vouchers-json", json=payload, headers=HDR)
+results.append(check("用例4b 再次重发仍 already_imported 且 batch 不变", r4b.status_code == 200 and j4b_is_already(r4b, j4), f"body={r4b.text[:200]}"))
+
 # ── 用例5: 无 X-BOT-KEY → 401 ──
 r5 = client.post("/api/cma/cash/import/vouchers-json", json=payload)
 results.append(check("用例5 无X-BOT-KEY 401", r5.status_code == 401, f"status={r5.status_code}"))