Full duplex: Streaming HTTP request & response

The recently announced ([link](https://blog.cloudflare.com/bringing-node-js-http-servers-to-cloudflare-workers/#whats-supported)) `node:http` support notes:

> What's Supported
> - Standard HTTP methods (GET, POST, PUT, DELETE, etc.)
> - Request and response headers
> - Request and response bodies
> - Streaming responses
> - Basic authentication

Is it possible to also support streaming requests? This, for example, will help with clients pool connections to databases (like Postgres) through Workers.

Kenton says supporting bidi HTTP is a matter for the transport-layer appliances at the perimeter, but encouraged me to open an issue here with workerd anyway ([ref](https://github.com/duckdb/duckdb-wasm/discussions/430#discussioncomment-13208635)).

No files, tests, or entry points are named. Start by tracing how workerd handles node:http request and response bodies, then investigate the transport-layer limitations referenced in the issue. Done means establishing whether full-duplex streaming requests are feasible and defining the implementation scope or constraints.

Written by the indexing model from the issue text.