Support custom model name for Anthropic and Google Gemini etc.

[narapeka]

Glad to see that KILO already supports custom API URL for these providers.
However, the model names are fixed values in the dropdown, which cannot be edited.
Please consider to add a "manual value" option in the dropdown to allow custom model name.

This is important for private deployed models - enterprises will deploy models to have a custom API URL, and also they often rename the models (for example from claude-sonnet-4-2025xxxx to just claude-sonnect-4)

[ramhaidar]

+1 This ☝️