feat(sense): T-G3 标签+校准（labeler 四规则推导 + split-conformal + last-good）

- labeler.py：derive_true_tier 纯函数（规则0 人工优先 / plan_multi->T3 /
  失败->下一档(T3保持) / 成功->executed / 空结果跳过）+ derive_true_tiers
  批量回填 + 180d 留存清理
- calibrate.py：compute_thresholds（τ1/τ3 分组扫描——并列分数整组判定，
  精度 >= 1-α 的最大覆盖阈值；<min_labels -> ok=False 沿用 last-good）；
  save_thresholds 工件落盘+登记；load_active 回退链 active->同kind扫描->last-good->保守值
- store：all_observations/list_artifacts 支撑方法
- 测试 +9（四规则/批量清理/覆盖达标/标签不足/工件往返与回退），全量 395 passed

gateway/sense/store.py

@@ -116,6 +116,14 @@ class SenseStore:
                 " WHERE true_tier != ''").fetchone()
         return int(row["c"])
 
+    def all_observations(self, limit: int = 200000) -> List[Dict[str, Any]]:
+        """全量遍历（labeler 夜间推导输入；量大时可分页）。"""
+        with self._lock, self._connect() as conn:
+            rows = conn.execute(
+                "SELECT * FROM tier_observations ORDER BY id LIMIT ?",
+                (limit,)).fetchall()
+        return [dict(r) for r in rows]
+
     def purge_older_than(self, ts: float) -> int:
         """留存清理（D-G6：默认 180 天，夜间任务顺带）。"""
         with self._lock, self._connect() as conn:
@@ -154,6 +162,14 @@ class SenseStore:
                 " ORDER BY created_ts DESC LIMIT 1", (kind,)).fetchone()
         return dict(row) if row else None
 
+    def list_artifacts(self, kind: str) -> List[Dict[str, Any]]:
+        """同 kind 工件按时间倒序（load_active 的 last-good 扫描用）。"""
+        with self._lock, self._connect() as conn:
+            rows = conn.execute(
+                "SELECT * FROM sense_artifacts WHERE kind = ?"
+                " ORDER BY created_ts DESC", (kind,)).fetchall()
+        return [dict(r) for r in rows]
+
     # ---------- 自省 ----------
     def table_names(self) -> List[str]:
         with self._lock, self._connect() as conn: