feat(i18n,zhipu): 中文化主要页面 & 修复智谱免费 VLM 连接失败

[CHANGGELY]

• 前端：新增 i18n 资源，首页/监控/设置等中文化，默认语言 zh，保留切换
• 后端：规范化 baseUrl，移除重复的 /chat/completions；VLM 校验改为 image_url+text；Embedding 别名映射 Doubao-embedding-large → doubao-embedding-large-text-240915
• 配置：默认设智谱 VLM 与豆包 Embedding 的 baseUrl 与模型名；API Key 通过环境变量，不硬编码

提升：降低使用门槛，支持智谱免费 VLM 正常连通，保留混合供应商用法

Description

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Closes: #294

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[KashiwaByte101]

can you share i18n result image here

[qin-ctx]

配置文件改动可以去除，对现有改动有影响，不要提交用于测试的内容