[Feature]I hope to add configuration parameters for the ollama model.

[ugaxm]

Problem Description
I am using ollama to call qwen2.5:7b and found that in the case of long texts, the context tokens seem to be limited to 2000-4000 tokens. Even setting the maximum conversation count to "unlimited" does not work. After consulting the official ollama documentation, I discovered that by passing the option ctx_num: 32000, the context length of qwen2.5:7b can be increased.

Proposed Solution
In the model configuration of ollama, a new field ctx_num has been added to facilitate users in modifying the context length.

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问题描述
我在使用ollama调用qwen2.5:7b，发现长文本的情况下，上下文token似乎只有2000-4000token。即使把最大对话数量设为“无限制”也不起作用。查阅ollama官方文档，发现可以通过传入ctx_num: 32000 这个options，把qwen2.5:7b的上下文长度加大。

解决思路
在ollama的模型配置中，新增ctx_num字段，方便用户修改。