code-to10 v6 A14 batch2: test E402/F401 cleanup plus touched-file residual E,F cleanup

(cherry picked from commit 1db02545f74c96b3b92be4fc32954659cec1f814)

Reconcile-conflict: A14b E402 imports referencing cloud.handler_core (does not exist here; core methods live in server.py) — kept HEAD imports with incoming's noqa: E402 markers, dropped the unused core_mod import (verified unused elsewhere in both files).

cloud/tests/test_v2cov_server_handlers5.py

@@ -8,7 +8,6 @@ stubbed only to drive the handler's own error mapping.
 """
 
 import os
-import socket
 import sqlite3
 import sys
 import tempfile
@@ -21,12 +20,11 @@ from unittest import mock
 REPO_ROOT = Path(__file__).resolve().parents[2]
 sys.path.insert(0, str(REPO_ROOT))
 
-from cloud.server import (
+from cloud.server import (  # noqa: E402
     CloudControlPlaneHandler,
     _auth_store,
     init_db,
 )
-from cloud.sub2api import Sub2apiError as _Sub2apiError
 
 
 def _handler(db_path, upload_dir=None, tenants_root=None):