Allow `-max-ai-credits=0` when using local models

### Describe the feature or problem you'd like to solve

I'd like to be able to use local models with `/remote` without the possibility of accidentally using credits in that session

### Proposed solution

Remote the validation on `-max-ai-credits` that requires that it is >= 30.

### Example prompts or workflows

_No response_

### Additional context

The limit of 30 seems totally arbitrary, and when using a local model it doesn't mean anything. When testing with local models, it would be nice to know for sure that we can't accidentally use credits.

先找出 `-max-ai-credits` 選項的驗證邏輯，以及使用 `/remote` 時識別本機模型的程式碼。確認目前的最小值為 30，接著驗證本機模型工作流程接受值 0，並確保工作階段不會意外使用額度。

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