feat: TCP-only builds; TCP options and timeouts; receives that report and keep what arrived

- --no-quic leaves QUIC, HTTP/3 and WebTransport out of the build, and with
  them msquic: a consumer that only needs TCP builds no msquic. The flag
  isn't passed on to dependencies.
- --local takes Crafter.Thread from the sibling checkout, as the other
  Crafter projects do.
- ClientTCP gains SetNoDelay, SetReceiveTimeout, a connect timeout and
  SocketTimeoutException.
- TCP receives return the bytes that arrived:
  - RecieveSync(n) returned the whole buffer when fewer had come;
  - RecieveUntilCloseSync truncated what it had read;
  - a signal (EINTR) during a receive threw where it should wait on;
  - RecieveSync(size, buffer) returns the count and throws like the others;
  - a receive of no bytes returns at once: recv's 0 for it isn't a close.
- Every TCP *Async receive takes an onError(std::exception_ptr): an
  exception escaping a ThreadPool task ended the program. An empty onError
  drops the error.
- QUIC streams:
  - async receives deliver an empty chunk on close, as the browser build does;
  - RecieveUntilFullAsync gives what arrived on a stream that closes early;
  - RecieveUntilFullSync takes all it asked for or nothing, under one hold
    of the lock, so what did arrive stays for the next receive and no
    other receive can take bytes from among it;
  - SendAsync's callback hears whether the send went out (bool sent): native,
    browser, the JS bridge and the example.
- msquic is pinned to v2.6.3 and built against the system OpenSSL
  (QUIC_TLS_LIB=openssl, 3.5 or newer). Its bundled quictls read the system's
  openssl.cnf, and the Flatpak runtime's (a PKCS#11 engine, with
  config_diagnostics on) made it fail to initialise. The README says to use
  --no-quic where the distro's OpenSSL is older.
- Tests now register on any Linux triple: they never ran under the Flatpak's
  x86_64-unknown-linux-gnu. New: ShouldBuildWithoutQUIC, ShouldConfigureTCP,
  ShouldRecieveTCP, ShouldReportClosedQUICStream.

Breaking: SendAsync's callback takes a bool, the TCP *Async receives take
an onError, and RecieveSync(size, buffer) returns the count.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

interfaces/Crafter.Network.cppm

@@ -5,18 +5,24 @@ export module Crafter.Network;
 
 export import :ClientTCP;
 export import :ListenerTCP;
+export import :HTTP;
+#ifndef CRAFTER_NETWORK_NO_QUIC
+// HTTP/3, QUIC and WebTransport: over msquic natively, over the browser's
+// WebTransport in wasm. A native build with --no-quic leaves them out.
 export import :ClientHTTP;
 export import :ListenerHTTP;
-export import :HTTP;
 export import :ClientQUIC;
 export import :ListenerQUIC;
 export import :WebTransport;
+#endif
 #ifndef CRAFTER_NETWORK_BROWSER
+#ifndef CRAFTER_NETWORK_NO_QUIC
 // Exposed so user code can build WebTransport clients by hand against a
 // ClientQUIC until we ship a ClientWebTransport wrapper. Most callers do
 // 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;
+#endif
 // 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.