feat(http1): add an HTTP/1.1 client and listener

HTTP/3-only is not a deployable position yet: plenty of clients, proxies
and CI tooling still speak nothing but HTTP/1.1. This adds that path
using the request/response types the HTTP/3 stack already uses, so a
route handler or call site moves between the two protocols by changing
the class name.

- :HTTP1 — transport-free wire format. Serialisation with the framing
  headers owned by the serialiser, and an incremental parser that takes
  arbitrary socket chunks and yields one message at a time: keep-alive,
  pipelining, content-length and chunked bodies (with trailers),
  read-to-EOF responses, interim 1xx skipping, HEAD/204/304 framing and
  Expect: 100-continue. Ambiguous framing is rejected rather than
  guessed at (content-length with transfer-encoding, disagreeing
  content-lengths, whitespace before a colon), and CR/LF in a value we
  are asked to serialise is refused.
- ClientHTTP1 — persistent connection, redialling once when a pooled
  connection turns out to have been closed by the peer, which is the
  race HTTP/1.1 keep-alive cannot avoid. Nothing is replayed after a
  response byte has arrived.
- ListenerHTTP1 — one thread per connection (keep-alive connections are
  idle most of their life and would pin every ThreadPool thread),
  automatic Date, HEAD, 100-continue, handler-requested close, idle and
  request timeouts, and 400/404/500 responses. Routes fall back to the
  query-stripped path so `/thing?x=1` reaches the handler for `/thing`.

No TLS: this is `http://` only. Encrypted traffic still goes over
HTTP/3, or through a TLS-terminating proxy.

Tests: codec unit tests including the malformed inputs above, a
client/server round-trip, keep-alive and stale-connection recovery, a
10 MiB body both ways, and interop both directions against curl and
python3's http.server (skipped when those are not installed).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

interfaces/Crafter.Network.cppm

@@ -17,4 +17,10 @@ export import :WebTransport;
 // not need the HTTP/3 frame helpers directly. Excluded from the browser
 // build — HTTP3 uses throw and the wasm target runs with -fno-exceptions.
 export import :HTTP3;
+// HTTP/1.1 over TCP, for peers that are not ready for HTTP/3. Native only:
+// in the browser this job is already done by fetch() behind :ClientHTTP,
+// and these partitions use exceptions and POSIX sockets.
+export import :HTTP1;
+export import :ClientHTTP1;
+export import :ListenerHTTP1;
 #endif