Add support for OpenAI's gpt-5.2-codex

Reference:
- https://openai.com/index/introducing-gpt-5-2-codex/
- https://platform.openai.com/docs/models/gpt-5.2-codex

Author: PeterDaveHello

pr_agent/algo/__init__.py

@@ -40,6 +40,7 @@
     'gpt-5.2': 400000,  # 400K, but may be limited by config.max_model_tokens
     'gpt-5.2-2025-12-11': 400000,  # 400K, but may be limited by config.max_model_tokens
     'gpt-5.2-chat-latest': 128000,  # 128K, but may be limited by config.max_model_tokens
+    'gpt-5.2-codex': 400000,  # 400K, but may be limited by config.max_model_tokens
     'o1-mini': 128000,  # 128K, but may be limited by config.max_model_tokens
     'o1-mini-2024-09-12': 128000,  # 128K, but may be limited by config.max_model_tokens
     'o1-preview': 128000,  # 128K, but may be limited by config.max_model_tokens
@@ -223,6 +224,7 @@
     "o4-mini-2025-04-16",
     "gpt-5.1-codex",
     "gpt-5.1-codex-mini",
+    "gpt-5.2-codex",
     "gpt-5-mini"
 ]