Add GPT-5.4 Codex mythos artifact

Co-authored-by: Codex <codex@openai.com>

models/gpt-5-4-xhigh.json

@@ -6,6 +6,13 @@
   "artifactDir": "gpt-5-4/codex-xhigh",
   "order": 31.5,
   "runs": {
+    "mythos-craft": {
+      "note": {
+        "zh": "在 Codex CLI 中以 GPT-5.4（xhigh 思考配额）生成并整理为单文件 HTML 产物。",
+        "en": "Generated by GPT-5.4 (xhigh effort) inside Codex CLI and packaged as a single-file HTML artifact."
+      },
+      "contributor": "Nagi-ovo"
+    },
     "pelican-cycling": [
       {
         "note": {