P0 security batch: true global admin, quota gates on all spending paths, default quota for quota-less users, fix-review author trust + docker/owner attribution, GitHub App setup issuer binding, real cancel kill, wider shell env exclusion

- CODEX_GLOBAL_ADMINS replaces maintainer-derived global admin;
  admin endpoints (quotas, sweep, backup, push dispatch) fail-closed
  403 when unset, with audit on allow and deny.
- continue/followups/messages/retry check both caller and original
  creator quotas (USD + unpriced token cap), 402 on either overrun.
- Quota-less users now get the #86 default quota instead of unlimited;
  init_db backfills and OAuth create/bind/existing-login branches
  INSERT OR IGNORE a default row; explicit NULL row stays unlimited.
  user_quotas added to migration tables.
- /fix-review: untrusted authors rejected before dedup claim, no task;
  trusted tasks force executor=docker, created_by=project owner, owner
  quota gate, prompt is a fixed template plus a 2000-char excerpt.
- GitHub App setup state only issued by global admins, state rows bind
  issued_by (ALTER-compatible for old DBs), callback rejects issuers
  no longer in the admin list without consuming the state.
- Cancel: popen poll checks DB status every second, Docker path runs a
  cancel watchdog that kills by container name, write-back is CAS-guarded
  so late results never overwrite a new status.
- SHELL_ENV_EXCLUDE adds *_TOKEN, *_AUTH*, *_CREDENTIAL*, *API_KEY*;
  comment states the residual risk: same-UID /proc environ remains
  readable, true isolation needs UID separation or hidepid.
- Tests: new cloud/tests/test_p0_security.py (17 cases); old tests
  updated to the new semantics (admin env, default quota, trusted
  fix-review author) without weakening any gate.

cloud/tests/test_github_app.py

@@ -289,6 +289,10 @@ class AppHttpTestCase(unittest.TestCase):
         self.db_path = os.path.join(self.tmp.name, "control.db")
         self.auth = AuthStore(self.db_path)
         self.user_a, self.key_a = self.auth.create_user("user-a")
+        # P0 安全批后：setup state 只限全局管理员，本用例里
+        # user-a 即管理员。
+        self._old_admins = os.environ.get("CODEX_GLOBAL_ADMINS")
+        os.environ["CODEX_GLOBAL_ADMINS"] = self.user_a
         self.server = create_server(self.db_path, "127.0.0.1", 0)
         self.port = self.server.server_address[1]
         self.thread = threading.Thread(
@@ -307,6 +311,10 @@ class AppHttpTestCase(unittest.TestCase):
         self.tmp.cleanup()
         os.environ.pop("GITHUB_APP_PUBLIC_BASE", None)
         os.environ.pop("GITHUB_WEBHOOK_SECRET", None)
+        if self._old_admins is None:
+            os.environ.pop("CODEX_GLOBAL_ADMINS", None)
+        else:
+            os.environ["CODEX_GLOBAL_ADMINS"] = self._old_admins
 
     def _req(self, method, path, body=None, key=None, headers=None):
         conn = http.client.HTTPConnection("127.0.0.1", self.port, timeout=10)
@@ -488,7 +496,8 @@ class AppHttpTestCase(unittest.TestCase):
         payload = {
             "action": "created",
             "comment": {"id": 777, "body": "please /fix-review this",
-                        "user": {"login": "octo"}},
+                        "user": {"login": "octo",
+                                 "author_association": "COLLABORATOR"}},
             "issue": {"number": 5},
             "repository": {"full_name": "octo/a"}}
         # 同一评论送两遍，delivery_id 不同（模拟手动 + App 双通道）。