feat: 支持 Anthropic（Claude）作为内置 LLM 提供商 || feat: Support Anthropic (Claude) as built-in LLM provider

目前 HiClaw 内置了 `qwen` 和 `openai-compat` 两种 LLM 提供商，希望能增加对 Anthropic API 的原生支持。
如果理解的没错，Higress 似乎本身已经内置了 `claude` 提供商类型，可以自动处理 OpenAI → Anthropic 的协议转换，实现起来改动不大：

- 在 initializer 的 switch 里加 `case "anthropic"`，Type 设为 `"claude"`
- 安装脚本的提供商选择菜单里加上 Anthropic 选项
- 无需改动 config 结构体，`LLMAPIKey` / `LLMProvider` 已经是通用字段

这样用户就可以通过 `HICLAW_LLM_PROVIDER=anthropic` 直接使用 `claude-sonnet-4-6`、`claude-opus-4-7` 等模型了。

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HiClaw currently has two built-in LLM providers, `qwen` and `openai-compat`, and we hope to add native support for the Anthropic API.

Higress itself has built-in `claude` provider type, which can automatically handle the protocol conversion from OpenAI → Anthropic, and the implementation does not change much:

- Add `case "anthropic"` to the switch in the initializer and set Type to `"claude"`
- Added Anthropic option to the provider selection menu of the installation script
- No need to change the config structure, `LLMAPIKey` / `LLMProvider` are already common fields

In this way, users can directly use models such as `claude-sonnet-4-6` and `claude-opus-4-7` through `HICLAW_LLM_PROVIDER=anthropic`.