Add GPT 5.1 codex models to verified models list (#1358)

Co-authored-by: Engel Nyst <engel.nyst@gmail.com>

Author: Chesars

openhands-sdk/openhands/sdk/llm/utils/verified_models.py

@@ -1,4 +1,7 @@
 VERIFIED_OPENAI_MODELS = [
+    "gpt-5.1-codex-max",
+    "gpt-5.1-codex",
+    "gpt-5.1-codex-mini",
     "gpt-5-codex",
     "gpt-5-2025-08-07",
     "gpt-5-mini-2025-08-07",