feat(cli): reach instances over QUIC

crafter-debug had a placeholder transport that reported every instance
unreachable. Cli::ConnectQuic dials 127.0.0.1 at the port in the
discovery record on the first call, keeps the connection for the next,
and dials again after one is lost. Each call opens a stream, sends the
request with a FIN, and reads lines: one with a result or an error is
the reply, anything before it a stream line for onLine, which runs on
the calling thread so a slow terminal never stalls msquic's worker.
Past the deadline the stream is aborted and the call times out.

The handshake gives up after 3 s, and keep-alives every 2 s hold a
quiet follow or a long wait open under the 10 s idle timeout. main
starts a pool with one worker, which Network reports some failures on,
and ends with _Exit once Run has closed its connections, since msquic's
teardown at exit waits on connections.

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

interfaces/Crafter.Debug.Cli-Quic.cppm

@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: LGPL-3.0-only
+// SPDX-FileCopyrightText: Copyright (C) 2026 Catcrafts®
+
+// The client's transport: a Connection over QUIC to an instance's port on
+// 127.0.0.1, one stream per request. The library's :Transport describes the
+// wire.
+export module Crafter.Debug.Cli:Quic;
+import std;
+import Crafter.Debug.Core;
+import :Client;
+
+export namespace Crafter::Debug::Cli {
+    // Connects on the first call and keeps the connection for later ones,
+    // reconnecting after one is lost. Needs Crafter.Thread's pool running.
+    std::unique_ptr<Connection> ConnectQuic(const InstanceRecord& instance);
+}

interfaces/Crafter.Debug.Cli.cppm

@@ -1,6 +1,8 @@
 // SPDX-License-Identifier: LGPL-3.0-only
 // SPDX-FileCopyrightText: Copyright (C) 2026 Catcrafts®
 
-// The crafter-debug client, as a library so tests can run it in process.
+// The crafter-debug client, as a library so tests can run it in process:
+// the program (:Client) and its QUIC transport (:Quic).
 export module Crafter.Debug.Cli;
 export import :Client;
+export import :Quic;