Support Ollama Context Size Configuration

[homjay]

例行检查

• [ x] 我已确认目前没有类似 issue
• [ x] 我已确认我已升级到最新版本
• [ x] 我已完整查看过项目 README，尤其是常见问题部分
• [x ] 我理解并愿意跟进此 issue，协助测试和提供反馈
• [x ] 我理解并认可上述内容，并理解项目维护者精力有限，不遵循规则的 issue 可能会被无视或直接关闭

问题描述

In ollama, the default context size is 2048, which causes long texts to be unable to track instructions.

one-api has added relevant settings in the request, but they are only effective for non-OpenAI API requests. For example:
songquanpeng/one-api#1694

For applications that only support the OpenAI API, this is very inconvenient.

预期结果

It would be great if ollama's native parameter num_ctx could be supported, and ideally, it should be possible to override the existing variable directly in the settings.