[ENHANCEMENT] Add userAgent to Bedrock Client

[ajjuaire]

Problem (one or two sentences)

Use defaultUserAgentProvider in RooCode like Cline did in cline#6821 to specify which version of Roo is being used with the Bedrock provider. This will increase observability of errors per userAgent and will be easier for Bedrock users to detect regressions between different Roo versions.

Context (who is affected and when)

Bedrock Users

Desired behavior (conceptual, not technical)

Something like roo-cline/3.28.16 is sent as userAgent to bedrock

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

Roo Code Task Links (optional)

No response

Acceptance criteria (optional)

No response

Proposed approach (optional)

No response

Trade-offs / risks (optional)

No response

[roomote]

I'm exploring a potential fix for adding userAgent to the Bedrock Client and will open a PR to share progress.

[roomote]

Opened PR #8663 with my attempt at addressing this issue. The implementation adds a userAgent to the Bedrock client using the defaultUserAgentProvider configuration, similar to Cline's approach but adapted to follow Roo Code's conventions. Feedback welcome!