Integrate Cloudflare Durable Objects for Rate Limiting, WebSockets, and Deduplication

[jaypatrick]

Implement Cloudflare Durable Objects in the Worker runtime:

• Replace rate limiting KV logic with DO (atomic increments, strong consistency per-API-key or per-IP)
• Prototype WebSocket hibernation for long-lived connections
• Optional: Use DO for in-flight compile job deduplication or session presence tracking

Reference: https://hono.dev/examples/cloudflare-durable-objects/