[Feature] Add O3.fan as Provider

[zerob13]

Is your feature request related to a problem? Please describe.

The application currently lacks support for the O3.fan API provider. O3.fan offers access to a variety of powerful large language models. Not being able to use O3.fan limits the choice of providers and prevents users from accessing its unique model offerings and competitive pricing.

Describe the solution you'd like

I would like to request the addition of O3.fan as a new provider. Since O3.fan offers an OpenAI-compatible API, the integration should be relatively straightforward. The key information for the provider would be:

• Provider Name: O3.fan
• API Base URL: https://api.o3.fan/v1
• Authentication: Bearer Token using an API Key.

Describe alternatives you've considered

Using other available providers, but they may not offer the specific models or pricing that O3.fan provides.

Additional context

The official website for the service is: https://o3.fan/

Below is a sample cURL command demonstrating how to call their OpenAI-compatible chat completions endpoint:

curl -X POST https://api.o3.fan/v1/chat/completions \
-H "Authorization: Bearer YOUR_O3_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "gpt-4o",
"messages": [{
    "role": "user",
    "content": "Explain the importance of fast language models"
}]
}'

---

功能请求：添加对 O3.fan 的支持

你的功能请求是否与某个问题有关？请描述一下。

当前应用不支持 O3.fan 作为 LLM provider。O3.fan 提供了多种强大的语言模型。缺少对它的支持，使用户无法利用其独特的模型和有竞争力的定价，限制了 Provider 的选择范围。

请描述你希望的解决方案

希望能支持添加 O3.fan 作为一个新的 Provider 选项。O3.fan 提供了与 OpenAI 兼容的 API，因此集成应可参照现有的 OpenAI provider 实现。关键配置信息如下：

• Provider 名称: O3.fan
• API Base URL: https://api.o3.fan/v1
• 认证方式: 使用 API 密钥进行 Bearer Token 认证。

请描述你考虑过的其他替代方案

使用其他已支持的 Provider，但它们可能无法提供 O3.fan 所特有的模型或定价方案。

附加背景

该服务的官方网站是：https://o3.fan/

下方是一个调用其与 OpenAI 兼容的 chat/completions 接口的 cURL 请求示例：

curl -X POST https://api.o3.fan/v1/chat/completions \
-H "Authorization: Bearer 你的O3_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "gpt-4o",
"messages": [{
    "role": "user",
    "content": "解释一下为什么快速的语言模型很重要"
}]
}'

[CodeYHJ]

@zerob13 实现这个feature，是需要把chat.ts中的逻辑按功能拆分再集成吗？

[zerob13]

@zerob13 实现这个feature，是需要把chat.ts中的逻辑按功能拆分再集成吗？

不是的，你可以参考下类似 DeepseekProvider AihubmixProvider 实现这家供应商的api，基本上就是main层实现即可，renderer层只需要增加icon和配置，只是 chat 拆分的时候提到过这类需求。
类似 pr #993