test: annotate the legacy locale I/O wrapper

manifests/context-packs/skill-triggers@1.json

@@ -10,7 +10,7 @@
     "id": "hand-seeded",
     "source": "manual-curation-pending-regeneration"
   },
-  "registryDigest": "191d5ab399be507136bcb961c1c6ccc0502410ca93a70e30250516f08f717d6d",
+  "registryDigest": "18c3ce00385a4c84d03f224208095d2efdc6f3b3486ed561c970080fcc2e88d4",
   "schemaVersion": 1,
   "triggers": {
     "skill:agent-runtime-gateway-smoke-test": [

skills/skill-comply/tests/test_utf8.py

@@ -142,12 +142,16 @@ def test_utf8_boundaries_under_legacy_encoding() -> None:
         import locale
         import os
         import sys
+        from typing import IO, Any
 
         assert sys.flags.utf8_mode == 0
         if os.name == "nt":
             # Windows ignores LC_ALL for text I/O; emulate its legacy default.
             original_open = io.open
-            def legacy_open(file, mode="r", buffering=-1, encoding=None, *args, **kwargs):
+            def legacy_open(
+                file: Any, mode: str = "r", buffering: int = -1,
+                encoding: str | None = None, *args: Any, **kwargs: Any,
+            ) -> IO[Any]:
                 if "b" not in mode and encoding in (None, "locale"):
                     encoding = "cp1252"
                 return original_open(file, mode, buffering, encoding, *args, **kwargs)