[FEATURE] Add model definition for bedrock eu nova-lite

[mkon]

Scope check

• This is core LLM communication (not application logic)
• This benefits most users (not just my use case)
• This can't be solved in application code with current RubyLLM
• I read the Contributing Guide

Due diligence

• I searched existing issues
• I checked the documentation

What problem does this solve?

In EU we must use eu.amazon.nova-2-lite-v1:0 and not us.amazon.nova-2-lite-v1:0. I got it to work locally by using a fork of the gem with manually updated models.json where i simply cloned the us model and updated the id and hosting localtion.

Proposed solution

Update the models.json to include eu.amazon.nova-2-lite-v1:0

Why this belongs in RubyLLM

Afaik it is not possible to inject custom models.