fix: audit batch 2 visibility (I-1 shadow dropped rows, I-2 partial policy failure, I-5 failure policy table)

- I-1: evaluate_shadow counts dropped rows by cause (unparseable /
  unknown_tier / explicit / duplicate) with the identity
  audit_rows_total == routed_task_n + dropped_total; the shadow
  endpoint passes created_at/id through and reports audit totals
  next to sample counts.
- I-2 (option b): parse logs a warning naming each tier dropped for
  an invalid mode/requires; load attaches partial_failures to the
  policy; the worker records a task-level
  worker_routing_policy_load_failed audit for partial failures
  (same action as full failure, detail says failure=partial);
  the shadow report carries the policy fingerprint, dropped tiers
  and partial failures (no task context on that path, so no
  task-level audit there).
- I-5: coordinator gate audit lookup failure now raises
  _CoordGateLookupFailed and the merge converts it to escalate
  (no requeue, no round consumed); persisted-model lookup failure
  and required-tools check failure each write a named audit row
  before falling through to dispatch/allow; audit-loop evaluate
  failure stays escalate (regression test).
- Test fixtures: coordinator suites build audit_log via AuthStore
  as production's first real audit does, since their stubbed
  _audit never creates the table.

cloud/tests/test_audit_loop_coord_fix.py

@@ -25,11 +25,13 @@ from pathlib import Path
 from types import SimpleNamespace
 
 try:
+    from cloud.auth import AuthStore
     from cloud.coordinator import build_report, evaluate_outcome
     from cloud.server import init_db
     from cloud.worker import Worker
 except ImportError:
     sys.path.insert(0, str(Path(__file__).resolve().parents[2]))
+    from cloud.auth import AuthStore
     from cloud.coordinator import build_report, evaluate_outcome
     from cloud.server import init_db
     from cloud.worker import Worker
@@ -111,6 +113,13 @@ class CoordFixTestCase(unittest.TestCase):
         self.tmp = tempfile.TemporaryDirectory()
         self.db_path = os.path.join(self.tmp.name, "control.db")
         init_db(self.db_path)
+        # Audit batch 2 (I-5)，与 test_audit_loop_coord.py 同款
+        # 理由：生产里 audit_log 由首次真实 _audit 经 AuthStore
+        # 建好，合流时表一定存在；本文件把 _audit 桩成列表，
+        # 表永远不会出现，夹具里按生产实际补建表，否则合流
+        # 测试会因缺表改走 escalate，与被测行为无关。
+        _store = AuthStore(self.db_path)
+        _store.conn.close()
         self.env = {"XCM_API_KEY": "test-placeholder"}
         self.audits = []
         self.worker = Worker(self.db_path, "/fake/host.py",
@@ -200,10 +209,14 @@ class CoordFixTestCase(unittest.TestCase):
         # 最旧 id 的子任务必须不在，且集合恰好 5000 条。
         conn = sqlite3.connect(self.db_path)
         try:
+            # Audit batch 2 (I-5)：setUp 已按生产实际经 AuthStore
+            # 建好含 id 自增列的 audit_log 表，建表改 IF NOT
+            # EXISTS——生产表与本测试要的表在 id 语义上一致，
+            # tie-break 断言不受影响。
             conn.execute(
-                "CREATE TABLE audit_log(id INTEGER PRIMARY KEY"
-                " AUTOINCREMENT, user_id TEXT, project_id TEXT,"
-                " action TEXT, detail TEXT,"
+                "CREATE TABLE IF NOT EXISTS audit_log(id INTEGER"
+                " PRIMARY KEY AUTOINCREMENT, user_id TEXT,"
+                " project_id TEXT, action TEXT, detail TEXT,"
                 " created_at DOUBLE PRECISION)")
             now = time.time()
             conn.executemany(