test(cma): clear 10 pre-existing baseline failures (cma-baseline-tests-cleanup-20260915)

No production code changed. Root causes were all test-side staleness:

- test_cash TestVoucherImport: fixture filename contained 'test' -> rejected by the intentional import guard (d71c7fe); renamed, and missing-columns case now asserts the column check is what returns 400

- test_budget_tech_improve TestP1ValueCollect: seeded voucher_details source rows; collector deliberately skips empty aggregates since d71c7fe (no more implicit 0), and preview call now passes an explicit period

- test_roadmap_r2r5 / test_budget / test_ai_suggestions: seeds hardcoded 2026-08 (authoring month) while detectors/rule engine use the current month -> replaced with current-period seeds

pytest tests/ -q -rf: 1094 passed, 1 xfailed, 0 failed (baseline was 10 failed, 1084 passed, 1 xfailed)

backend/tests/test_cash.py

@@ -234,7 +234,9 @@ class TestVoucherImport:
         buf.seek(0)
         return buf
 
-    def _upload(self, client, token, buf, fname="test_vouchers.xlsx"):
+    def _upload(self, client, token, buf, fname="vouchers_import.xlsx"):
+        """注意: 文件名不得含 test/示例/sample/demo 等测试标识——导入端点有生产防线
+        （d71c7fe「Excel导入示例文件防线」），含标识直接 400，与三条校验规则的用例无关。"""
         return client.post(
             f"{BASE}/import/vouchers", headers=auth_header(token),
             files={"file": (fname, buf,
@@ -315,3 +317,4 @@ class TestVoucherImport:
         buf = self._xlsx([["2026-08-01", "记-001", 100, 0]], cols=["日期", "凭证号", "借方金额", "贷方金额"])
         resp = self._upload(client, token, buf)
         assert resp.status_code == 400
+        assert "缺少必要列" in resp.json()["detail"]  # 断言是列校验拦下，而非文件名防线