feat(codex): add Tencent Hunyuan TokenHub preset with native Responses

Official TokenHub Codex docs (cloud.tencent.com/document/product/1823/133532)
confirm hy3 speaks the Responses API natively; the mandatory
disable_response_storage=true is already emitted by the config
generator. Models hy3/hy3-preview are text-only with a 256k context
window. Endpoint candidates include the official backup domain, while
the intl site is excluded because API keys are region-scoped.

tests/config/codexChatProviderPresets.test.ts

@@ -158,6 +158,11 @@ describe("Codex Chat provider presets", () => {
         { contextWindows: { "doubao-seed-2-1-pro-260628": 262144 } },
       ],
       ["Bailian", { contextWindows: { "qwen3-coder-plus": 1048576 } }],
+      // 腾讯 TokenHub 官方 Codex 文档确认 hy3 原生 Responses（2026-07-14）
+      [
+        "Tencent Hunyuan",
+        { contextWindows: { hy3: 256000, "hy3-preview": 256000 } },
+      ],
       // DeepSeek 官方 Codex 文档确认 deepseek-v4-flash 原生 Responses；
       // catalog 由后端按 deepseek.com host 镜像官方 models.json 生成
       [