Preserve thinking configuration when converting OpenAI requests to Claude format.
- Handle thinking.type with 'enabled' as default
- Preserve thinking.budget_tokens when present
- Preserve thinking.max_tokens when present
This enables proper thinking mode support for o1-series models
when routed through 9Router to Claude endpoints.
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>
(cherry picked from commit 65d80e9269cc6789cb1522b276e8b8399fddbcab)