feat(selector): 增加离线候选遍历与严格回放验证 Demo

- 新增 selector_candidate_demo，移除 provenance intent 后枚举候选 selector
- 对候选分支执行有界重建与严格 STEP 比较
- 仅在候选遍历完整且唯一 strict 通过时生成 selector 映射记录
- 增加 selector 候选搜索、预算限制和记录生成的测试
- 保持生产 selector resolver 不受 Demo 逻辑影响
- 更新 CADFS 能力台账，记录 IMPRINT 派生 profile 的 lineage selector 缺口

backend/engine/cdsl_engine/operation_contracts.py

@@ -31,12 +31,14 @@ def materialized_feature_contracts(profile: dict[str, Any]) -> dict[str, dict[st
         params_schema = raw.get("author_params_schema")
         injected_paths = raw.get("server_injected_paths")
         selector_policy = raw.get("selector_policy")
+        nested_selector_policies = raw.get("nested_selector_policies") or {}
         runtime_capability = raw.get("runtime_capability")
         if (
             not isinstance(shape, dict)
             or not isinstance(params_schema, dict)
             or not isinstance(injected_paths, list)
             or not isinstance(selector_policy, dict)
+            or not isinstance(nested_selector_policies, dict)
         ):
             raise ValueError(f"operation contract is incomplete for {atomic_id}")
         if not isinstance(runtime_capability, dict) or not all(
@@ -52,6 +54,8 @@ def materialized_feature_contracts(profile: dict[str, Any]) -> dict[str, dict[st
             raise ValueError(f"operation author params are invalid for {atomic_id}")
         if not all(isinstance(name, str) and name in properties for name in required):
             raise ValueError(f"operation required params are invalid for {atomic_id}")
+        if not all(isinstance(path, str) and isinstance(policy, dict) for path, policy in nested_selector_policies.items()):
+            raise ValueError(f"operation nested selector policies are invalid for {atomic_id}")
         materialized_required = list(dict.fromkeys(required))
         for path in injected_paths:
             if not isinstance(path, str):
@@ -67,6 +71,7 @@ def materialized_feature_contracts(profile: dict[str, Any]) -> dict[str, dict[st
             "requires_sketch": shape.get("sketch") == "required",
             "selector_slot": selector_policy.get("slot"),
             "selector_token_kind": selector_policy.get("token_kind"),
+            "nested_selector_policies": dict(nested_selector_policies),
             "runtime_capability": dict(runtime_capability),
         }
     return derived