feat (provider/perplexity): add sonar-deep-research model

[jhsu]

Background

New perplexity model sonar-deep-research is available.

Summary

Add sonar-deep-research model id to perplexity provider.

Verification

Ran generation using sonar-deep-research

[lgrammel]

Please add a changeset and update the perplexity provider docs page

[jhsu]

@lgrammel added changeset and the model to the table in the perplexity doc

[lgrammel]

Please run pnpm prettier-fix

[jhsu]

Ran and pushed. I'm on windows so had to make git not replace end of line lf with crlf 😅