Natural Memory NM2.1: 记忆路由器分叉、数据集缺陷修复与全轴评测证据

- 引入 MemoryRouterXL 与 v5/v6 流式多线程训练/编码管线
- 修复 prepare_memory_router_dataset 候选池重建缺陷（mega 家族 3568x 加速，输出逐字节相同）
- 修复 v5 被破坏的拒答与多跳标签（train 未知样本 319 -> 16319，multi_hop 平均正例 1.00 -> 2.00）
- 同存储预算下 V2-128 v6 逐轴 22/22 通过：Top-1 41.12% -> 94.62%，未知拒答 0.00% -> 100.00%
- 记录三条被实测推翻的显然优化（logits_to_keep=1 反而慢 55%、XL 容量未带来收益）
- 记忆手术跨架构可移植性 14/14，读写关闭时与原生模型逐位相同

data/zero_overlap_verification.json

@@ -0,0 +1,44 @@
+{
+  "verified_by": "verify_zero_overlap_dataset.py",
+  "data_dir": "V2_dpskw\\data\\zero_overlap",
+  "train": {
+    "split": "train",
+    "episodes": 1200,
+    "distinct_queries": 48,
+    "candidate_counts": [
+      24
+    ],
+    "unknown_episodes": 199,
+    "unknown_share_pct": 16.58,
+    "episodes_whose_query_lexically_matches_its_own_target": 0,
+    "episodes_with_a_lexical_distractor": 528,
+    "distractor_share_pct": 44.0,
+    "problems": 0,
+    "problem_examples": []
+  },
+  "eval": {
+    "split": "eval",
+    "episodes": 300,
+    "distinct_queries": 24,
+    "candidate_counts": [
+      24
+    ],
+    "unknown_episodes": 50,
+    "unknown_share_pct": 16.67,
+    "episodes_whose_query_lexically_matches_its_own_target": 0,
+    "episodes_with_a_lexical_distractor": 150,
+    "distractor_share_pct": 50.0,
+    "problems": 0,
+    "problem_examples": []
+  },
+  "split_disjointness": {
+    "shared_query_strings": [],
+    "disjoint": true
+  },
+  "checks": {
+    "no_query_overlaps_its_own_target": true,
+    "no_structural_problems": true,
+    "splits_disjoint": true
+  },
+  "all_checks_passed": true
+}