GET /api/dev/languages

获取支持的语言列表和翻译风格。

请求示例：

curl http://127.0.0.1:9527/api/dev/languages \
  -H "X-API-Key: dk_your_key_here"

响应示例：

{
  "ok": true,
  "data": {
    "languages": [
      { "code": "zh", "name": "中文（普通话）", "type": "major" },
      { "code": "en", "name": "英语", "type": "major" }
    ],
    "styles": [
      { "code": "standard", "name": "标准" },
      { "code": "casual", "name": "口语化" },
      { "code": "professional", "name": "专业" },
      { "code": "literary", "name": "文艺" }
    ]
  }
}