finetunes.public.list endpoint support in the Workers AI binding

### Describe the solution

It would be really great to get this endpoint supported natively by the binding: `https://api.cloudflare.com/client/v4/accounts/${process.env.CLOUDFLARE_ACCOUNT_ID}/ai/finetunes/public`

Allow for dynamic fetching of public LORAs in https://playground.ai.cloudflare.com

Start by locating the Workers AI binding entry point and its existing endpoint handling, then compare its conventions with the finetunes.public.list API endpoint. Verify that public LoRA data can be fetched dynamically for the Playground and add coverage for the supported endpoint behavior.

Written by the indexing model from the issue text.