* fix(api): update cacheReadsPrice for OpenAI GPT-4.1 models (#2887)
Set correct cacheReadsPrice (cached input price) for gpt-4.1, gpt-4.1 mini, and gpt-4.1 nano based on official OpenAI pricing. No changes to cacheWritesPrice as per current OpenAI documentation. This ensures prompt caching costs are accurately reflected for these models in cost calculations.
* Update more OpenAI cache prices
* Track cache tokens and cost correctly for OpenAI
* Update tests
---------
Co-authored-by: monotykamary <tom81094@gmail.com>