【New feature】 Allow increasing the quota limit per API key for AI providers

[haiyangzhijia]

Hello,

Could you add a balance limit and billing cycle setting for each API key configured under AI providers?

Use case:
Currently, I have multiple API keys, and each key has about $10 of monthly free quota. If the usage exceeds this limit, additional charges will be billed.

I would like to set a limit for each API key added to the AI provider. For example, when Key A reaches around $9 of usage, it would automatically be disabled, and the system would switch to another key that still has available balance, repeating this process across keys.

This would help prevent unexpected charges while managing multiple API keys with limited quotas.