Proposal: Fetch Server API

[jasnell]

Proposal: https://proposal-fetch-server.jasnell.me/

Purpose:

This specification defines a server-side API that:

• Uses standard Request and [Response (https://fetch.spec.whatwg.org/#response) without modification.
• Introduces a ServerContext for connection metadata, server capabilities, and lifecycle — the things that belong to the processing environment, not the HTTP message.
• Unifies HTTP/1.1, HTTP/2, and HTTP/3 behind one programming model.
• Handles both request/response exchanges and tunnel protocols (extended CONNECT).
• Defines primitives for the Capsule Protocol and HTTP Datagrams.