[FEATURE_REQUEST] Gemini 2.5 Flash Thinking Support

[equal-l2]

Have you searched for similar requests?

Yes

Is your feature request related to a problem? If so, please describe.

No response

Describe the solution you'd like

Preliminary support for Gemini 2.5 Flash was implemented in #3870, without thinking mode support. Thinking mode toggle (and hopefully thinking budget slider) is needed for full support.

Describe alternatives you've considered

No response

Additional context

No response

Priority

Medium (Would be very useful)

Are you willing to test this on staging/unstable branch if this is implemented?

Yes

[equal-l2]

I checked out the Gemini REST API docs, but they are far from complete about "thinking mode" and "thinking budgets" settings :cry: Google probably needs some more time to get the docs written up properly.