Parameterise Peripheral by its Devices and add CDChanger as one

src/avclan/device.hpp

@@ -0,0 +1,25 @@
+// copyright (C) 2026 Allen Hill <allenofthehills@gmail.com>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#pragma once
+
+#include "avclan.hpp"
+#include "avclan_defs.h"
+
+#include <concepts>
+#include <cstdint>
+
+namespace avclan {
+template <class T>
+concept Device = requires { std::integral_constant<uint8_t, T::id>{}; } &&
+                 requires(T dev, const AVCLAN_frame_t *in, AVCLAN_frame_t *out,
+                          detail::Error::Send err) {
+                   dev.init();
+                   dev.handle(in, out);
+                   dev.enable(out);
+                   dev.react(out, err);
+                   { dev.pending() } -> std::convertible_to<bool>;
+                   dev.resolvepending();
+                   dev.emit(out);
+                 };
+} // namespace avclan