Improve routing flexibility (drag & reorder primary models)

[niveku]

The routing feature is great, but it would be very helpful if the primary model selection could also be reordered via drag & drop.

Right now, reordering only applies to fallbacks, which limits flexibility. Being able to quickly change the priority of main models would make it much easier to:

Prioritize free-tier or quota-based models first
Quickly switch strategies depending on availability or performance
Fine-tune cost vs performance without reconfiguring everything

This would make routing much more dynamic and practical for real-world usage, especially when juggling multiple providers and quotas.

[SebConejo]

Hi @niveku, I see what you mean, I did that to give more information to the primary mode. I will improve it soon.