Mark CTO Stage 2 harness blocked on Case provider

WORKBOARD.yaml

@@ -57,6 +57,6 @@ items:
     owner: jp
   - id: CTO-WORK-012
     title: Stage 2 Harness Artificial Fixture Route
-    status: candidate
+    status: blocked
     source: sot/03-PROTOCOLS/CTO-CASE-STAGE2-ARTIFICIAL-FIXTURE-ISSUES.md
     owner: jp

tools/validate_cto_child.py

@@ -425,7 +425,7 @@ def main() -> int:
             "CTO-WORK-009": "validated",
             "CTO-WORK-010": "validated",
             "CTO-WORK-011": "validated",
-            "CTO-WORK-012": "candidate",
+            "CTO-WORK-012": "blocked",
         }
         for issue_id, expected in expected_statuses.items():
             checked.append(f"workboard_status:{issue_id}:{expected}")