chore: default model gpt-6.1-sol -> gpt-5.6-terra (#60)

Co-authored-by: host <host@test.local>

host.py

@@ -1459,7 +1459,7 @@ def main():
             return
         init_cfg = {
             "repo": args.repo or cfg.get("repo") or "",
-            "model": "gpt-6.1-sol", "effort": "low",
+            "model": "gpt-5.6-terra", "effort": "low",
             "sandbox": "workspace-write", "approval_policy": "never",
             "approval": "deny", "codex_home": "",
             "state": "host-state.json",
@@ -1474,7 +1474,7 @@ def main():
         print(f"配置文件已写：{config_path}，请按需改 repo/model 后再用")
         return
     # 有效配置（init/config 之外的命令都用它）
-    args.model = args.model or cfg.get("model") or "gpt-6.1-sol"
+    args.model = args.model or cfg.get("model") or "gpt-5.6-terra"
     args.effort = args.effort or cfg.get("effort") or "low"
     args.sandbox = args.sandbox or cfg.get("sandbox")
     args.approval_policy = args.approval_policy or cfg.get("approval_policy") or "never"