feat(tcp): a failed send or receive says which errno it failed with

Send() and the receives threw a bare std::runtime_error with the
strerror text, so a caller that reports the cause the way Python does -
"the connection broke ([Errno 104] Connection reset by peer)", which a
language model reads in Crafter.Review's SQL helper output - could not
tell the code. They throw SocketErrorException now, as a failed connect
already does: kind System, the errno, and the same message, still a
std::runtime_error. A receive timeout stays SocketTimeoutException and
a closed peer SocketClosedException.

ShouldReportIoErrors: a peer that resets the connection (SO_LINGER 0)
fails the next receive with ECONNRESET and a send into it with EPIPE
or ECONNRESET.

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

implementations/Crafter.Network-ClientTCP.cpp

@@ -38,10 +38,13 @@ namespace {
         return read;
     }
 
-    // A failed recv. EAGAIN is the receive timeout (SO_RCVTIMEO) running out.
+    // A failed recv. EAGAIN is the receive timeout (SO_RCVTIMEO) running out;
+    // anything else carries its errno, under the message a receive always
+    // threw.
     [[noreturn]] void ThrowRecieveError() {
-        if (errno == EAGAIN || errno == EWOULDBLOCK) throw SocketTimeoutException();
-        throw std::runtime_error(std::strerror(errno));
+        const int failure = errno;
+        if (failure == EAGAIN || failure == EWOULDBLOCK) throw SocketTimeoutException();
+        throw SocketErrorException(SocketErrorKind::System, failure, std::strerror(failure));
     }
 
     // One connect attempt to one address: a connected, blocking socket, or a
@@ -211,7 +214,8 @@ void ClientTCP::Send(const void* buffer, std::uint32_t size) const {
             throw SocketClosedException();
         } else if (status < 0) {
             if (errno == EINTR) continue;
-            throw std::runtime_error(std::strerror(errno));
+            const int failure = errno;
+            throw SocketErrorException(SocketErrorKind::System, failure, std::strerror(failure));
         }
         sent += static_cast<std::uint32_t>(status);
     }