Add Featherless AI as a provider

[DarinVerheijke]

What specific problem does this solve?

Adding Featherless aI as a provider to Roo Code to support inference through their API.

Additional context (optional)

No response

Roo Code Task Links (Optional)

No response

Request checklist

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

Interested in implementing this?

• Yes, I'd like to help implement this feature

Implementation requirements

• I understand this needs approval before implementation begins

How should this be solved? (REQUIRED if contributing, optional otherwise)

Following examples of other providers

How will we know it works? (Acceptance Criteria - REQUIRED if contributing, optional otherwise)

When I choose Featherless AI as a provider and enter an API key, I should be able to use a model from Featherless AI and see it work like any of the other providers that are available

Technical considerations (REQUIRED if contributing, optional otherwise)

Mostly re-using current code

Trade-offs and risks (REQUIRED if contributing, optional otherwise)

None