[FEATURE]: AutoFallback model #6212

Feature hasn't been suggested before.

• I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

It would be interesting to have a feature whereby when a model fails (especially errors due to exceeding the limit of requests/tokens per minute/hour/day), a switch to another is automatically made, always set by the user to continue the flow of thoughts/actions.
This would be useful because many providers, such as Google AI Studio, count as requests not only the initial user input, but also the result of executing a command, reading a file, etc., quickly reaching limits, especially for users on free plans (Gemini 3.0 Flash offers 20 RPD).

Example:

• Starts with Gemini 3.0 Flash - 20 requests
• Falls back to Gemini 2.5 Flash - 20 requests
• Falls back to Openrouter/Deepseek - 20 requests
• Uses free model (Big Pickle or Groq through Opencode Zen)