#10 feat: upgrade CAPTCHA solver to Llama 4 Scout

Summary

• replace the legacy LLaVA 1.5 7B image-to-text model with Cloudflare's multimodal Llama 4 Scout
• adapt to the text-generation response schema (response.response)
• make CAPTCHA inference deterministic and cap output at 8 tokens
• replace stale Hello World tests with assertions for the Worker's actual 405 behavior
• document the active model

Verification

• Source and current Cloudflare Workers AI model schema were reviewed.
• Local npm ci could not complete in the execution environment because its npm cache/registry setup repeatedly returned corrupted tarballs, so the test suite was not run locally.