feat(P2): contract + stack-IR kyverno-json policies + resolver wiring (REQ-295..299)

contract/ policies (4): require-id-pattern, require-env-in-enum,
require-infrastructure-min-1, forbid-unknown-fields — declarative
mirrors of contract.schema.json constraints.

stack-ir/ policies (3): require-tagging-standard (nova:owner/contract/
environment/cost-center tags — ports nova_tagging.py), forbid-public-ingress
(v1.0 demo rule, now declarative), require-encryption-by-default (v1.8
D-encryption-default — S3 + EBS encryption config).

core/contract_resolver.py: pre-resolve contract-policy evaluation (REQ-296)
+ post-resolve stack-IR-policy evaluation (REQ-298). Additive — the resolver's
return shape + exceptions unchanged; PCRs attach to stack_instance.policyResults.
Policy evaluation never breaks the resolver (confidence signal decides gate).

tests: test_stack_ir_policies.py + passing/failing fixtures. Skip-without-kj.
16 existing resolver tests unchanged.

---ci---
project: acdl
phase: 2
milestone: v1.25
status: execute
phase_role: execution
requirements:
  covered: [REQ-295, REQ-296, REQ-297, REQ-298, REQ-299]
  partial: []
---/ci---

core/contract_resolver.py

@@ -488,6 +488,25 @@ def resolve(contract_path, repo_root=None, environment_override=None):
     # Validate contract against schema
     jsonschema.validate(contract, contract_schema)
 
+    # v1.25 (REQ-296): pre-resolve policy evaluation — run the active
+    # PolicyEngine over the contract dict with the contract/ policy
+    # dir BEFORE resolving. Failures feed the `policyResults` on the
+    # stack instance (the confidence signal's `policy` input). The
+    # resolver does NOT exit on policy failure — the confidence signal
+    # decides the gate (consistent with the existing --soft-fail
+    # Checkov pattern).
+    contract_pcrs: list = []
+    try:
+        from core.policy_engine import get_engine, get_policy_root
+        _engine = get_engine()
+        _policy_root = get_policy_root()
+        contract_pcrs = _engine.evaluate(
+            contract, _policy_root / "contract", contract.get("id", "unknown")
+        )
+    except Exception:
+        # Policy evaluation must never break the resolver.
+        contract_pcrs = []
+
     # Interpolation (D-081): expand ${env.<field>} + ${contract.<field>}
     # tokens AFTER schema validation (the schema sees raw tokens, which are
     # valid strings) and BEFORE IR resolution (the resolver sees concrete
@@ -590,6 +609,12 @@ def resolve(contract_path, repo_root=None, environment_override=None):
         "data_sources": all_data_sources,
     }
 
+    # v1.25 (REQ-296): attach the pre-resolve contract-policy PCRs to
+    # the stack instance. The post-resolve stack-IR PCRs are appended
+    # after stack-schema validation (below).
+    if contract_pcrs:
+        stack_instance["policyResults"] = list(contract_pcrs)
+
     # Add the human-readable title
     if contract.get("name"):
         stack_instance["stack"]["title"] = contract["name"]
@@ -606,6 +631,28 @@ def resolve(contract_path, repo_root=None, environment_override=None):
     stack_schema = _load_schema(os.path.join(repo_root, "schemas", "stack.schema.json"))
     jsonschema.validate(stack_instance, stack_schema)
 
+    # v1.25 (REQ-298): post-resolve policy evaluation — run the active
+    # PolicyEngine over the resolved Stack IR with the stack-ir/ policy
+    # dir. The resulting PCRs are appended to the contract-policy PCRs
+    # on the stack instance (additive — the resolver's return value
+    # shape and exceptions are unchanged). The confidence signal
+    # consumes the merged list as its `policy` input.
+    try:
+        from core.policy_engine import get_engine, get_policy_root
+        engine = get_engine()
+        policy_root = get_policy_root()
+        stack_ir_pcrs = engine.evaluate(
+            stack_instance, policy_root / "stack-ir", contract.get("id", "unknown")
+        )
+        stack_instance.setdefault("policyResults", []).extend(stack_ir_pcrs)
+    except Exception:
+        # Policy evaluation must never break the resolver — the
+        # confidence signal decides the gate. A failure here means the
+        # engine is misconfigured; the contract PCRs (if any) are still
+        # present, and the confidence signal proceeds with whatever
+        # `policy` input it receives (possibly empty → 0.5 neutral).
+        pass
+
     return stack_instance