fix(rectification): anchor candidate windows to civil dates across midnight

Carry explicit local date intervals instead of inferring the day from clock
order. Cluster width, delivery, adoption, and reports keep the actual civil
date; adopted date is stored separately from the reported birth_date.

Algorithm identity is scoring-9 / spec-v5. Scoring weights, confirmation
thresholds, and Skill version are unchanged. Isolated Linux final-3 gates
passed; four pre-existing Python failures remain. This is not a production
release.

frontend/tests/rectification-confirmation-gate.test.ts

@@ -81,11 +81,11 @@ const diagnosticReport = JSON.parse(readFileSync(
     verified_minute_claim_allowed: boolean;
   };
 };
-// 原值：docs/research/sealed_holdout_rerun_2026_09_20.json
-// 新值：docs/research/sealed_holdout_rerun_cross_midnight_2026_09_20.json
-// 原因：BUG-981 修复后重跑另存报告；旧报告保留，确认门行为与阈值不变。
+// 原值：docs/research/sealed_holdout_rerun_cross_midnight_2026_09_20.json
+// 新值：docs/research/sealed_holdout_rerun_midnight_anchor_2026_09_21.json
+// 原因：午夜日期锚点修复的新冻结重跑另存报告；旧报告保留，确认门行为与阈值不变。
 const currentTreeRerun = JSON.parse(readFileSync(
-  new URL("../../docs/research/sealed_holdout_rerun_cross_midnight_2026_09_20.json", import.meta.url),
+  new URL("../../docs/research/sealed_holdout_rerun_midnight_anchor_2026_09_21.json", import.meta.url),
   "utf8",
 )) as {
   frozen_record: { implementation_sha256: string };
@@ -207,7 +207,7 @@ test("sealed holdout aggregates match the v3 report and still block confirmation
   );
   assert.equal(
     productHoldout.current_tree_scorer.source_report,
-    "docs/research/sealed_holdout_rerun_cross_midnight_2026_09_20.json",
+    "docs/research/sealed_holdout_rerun_midnight_anchor_2026_09_21.json",
   );
   assert.equal(currentTreeRerun.official_valid_independent_blind, false);
   assert.equal(productHoldout.current_tree_scorer.matches_metrics_scorer, false);