feat: coordinator audit-loop wiring at merge point

Parent audit loop sits after all children are aggregated and
before the parent final state; the single-task _audit_loop_wire
is never applied to parents or children. Parent gates are
per-child gates child:<name> (completed only); execution
failures map to one deterministic finding per child; subjective
findings are split off before evaluate and only audited as
needs_review. Gate-rejected children (capability/tool/approval
audit rows, or distinctive error markers) bypass evaluate and
escalate directly without consuming a round; tolerated, paused
and quota-missing parts are excluded, never findings. Rounds
are counted only in the parent task_audit_loop_state; on
pushback the packet is stored on the parent and split per failed
child into that child's audit_loop_packet column, consumed once
by the existing packet-injection path at next claim; pass and
escalate clear parent and child packets. POST /tasks now allows
audit_loop on coordinator parents (the old 400 rationale is
gone); children still take no external switch.

cloud/tests/test_audit_loop_wire.py

@@ -347,16 +347,19 @@ class ServerCreateTests(unittest.TestCase):
             {"project_id": pid, "prompt": "bad", "audit_loop": "yes"},
             self.owner_key)
         self.assertEqual(status, 400)
-        status, body = self._req(
+        # 协调员接线轨：父任务带 audit_loop 不再 400——此前拒绝
+        # 的理由是“父任务接线覆盖不到、接受即静默丢弃”，合流
+        # 接线（worker._coord_audit_loop_merge）落地后该理由已
+        # 消除；子任务仍不直接接受外部开关（worker 内部 INSERT
+        # 不写该列）。非法值仍 400。
+        status, task = self._req(
             "POST", "/tasks",
             {"project_id": pid, "prompt": "coord",
              "coordinator_parts": [{"name": "a", "prompt": "do a"}],
              "audit_loop": True},
             self.owner_key)
-        self.assertEqual(status, 400)
-        self.assertEqual(
-            body["error"],
-            "audit_loop cannot be used with coordinator tasks")
+        self.assertEqual(status, 201, task)
+        self.assertEqual(task["audit_loop"], 1)
 
 
 if __name__ == "__main__":