[ENHANCEMENT] add xhigh and max thinking mode to OpenRouter

[MINLEGO]

Problem (one or two sentences)

I noticed people who use OpenRouter can't use xhigh and max thinking mode, as the only value provided are "None, low, medium, high".
This is at least affecting Claudes and OpenAI models as they both provide a max and xhigh thinking mode.

It is not possible to bypass the issue by using the "OpenAI Compatible" provider, as "max" thinking mode is also not available.

Context (who is affected and when)

Happens when trying to use max and/or xhigh thinking mode with any provider

Desired behavior (conceptual, not technical)

max and xhigh thinking mode should be available in the dropdown, or an input for a custom thinking mode should be available.

Constraints / preferences (optional)

No response

Request checklist

• I've searched existing Issues and Discussions for duplicates
• This describes a specific problem with clear context and impact

Zoo Code Task Links (optional)

No response

Acceptance criteria (optional)

OpenAI models can be used with max and xhigh thinking mode using OpenRouter

Proposed approach (optional)

I am not familiar with the codebase, but adding the 2 thinking mode to the dropdown seams the easiest way to deal with the issue.

Trade-offs / risks (optional)

No response