Small dependency-free HTTP/1.1 listener for Snodo.Transport.StreamableHTTP.

It is intentionally a binding, not a web framework. Each accepted connection carries one request and closes after one response. Header admission happens in the connection process; admitted MCP work runs through the reusable bounded Snodo.Server.Executor. A peer disconnect while work is pending cancels that execution and tears down its reply owner.

:request_timeout bounds queue wait plus execution after HTTP admission; the transport's default ceiling is 30 seconds, including with an application-owned executor. Progress does not extend the deadline. Explicit :infinity disables this ceiling. Body reads and socket writes have their own transport bounds.

Connection and stream bounds, each a positive integer:

• :max_connections - the most connections open at once, default 1,024. A connection accepted at the limit is closed without being read.
• :head_timeout - milliseconds from accept until the request head must be complete, default 10,000. :read_timeout (default 5,000) still bounds each read; this deadline bounds the whole head, so a client that sends it a byte at a time is closed when the deadline passes.
• :body_timeout - milliseconds from the end of the head until the request body must be complete, default 10,000. Each body read returns what has arrived and waits at most :read_timeout; this deadline bounds the whole body, so a client that sends it a little at a time is closed when the deadline passes.
• :max_subscriptions - the most subscriptions/listen streams open at once, default 256. The executor holds one count per listener and returns a slot when the connection serving that stream exits. A stream over the limit is closed at its source and the request gets 503.

Applications that already run Plug, Bandit, or Cowboy can translate their request into Snodo.Transport.StreamableHTTP.Request and use the pure adapter directly instead of starting this listener.