chore: scaffold CMake build system

Add the CMake build for the Swift + C++ macOS port, mirroring the
refix layout: deps/ modules (Platform, Flags, Sanitizers, FindUnity),
per-module static libraries (usb, auth, mt76, gip, hid, api), a Swift
app entry point with a pure C bridge header, and a Unity test suite
behind BUILD_TESTING.

Swift requires the Ninja or Xcode generator; a guard in
CMakeLists.txt rejects anything else.

Co-Authored-By: qwen (qwen/qwen3.8-27b@q2_k_xl): scaffolded CMake build + tests

include/common/types.hpp

@@ -0,0 +1,49 @@
+#pragma once
+
+// ==============================================================================
+// Platform types and endianness helpers (user-space)
+// ==============================================================================
+// Replaces the kernel's __le16/__le32/guid_t machinery for user-space use.
+// All wire formats of the MT76 chip and the GIP protocol are little-endian;
+// these byte-wise helpers stay correct on any host endianness.
+// ==============================================================================
+
+#include <cstdint>
+
+namespace xone {
+
+// 128-bit GUID used by the GIP protocol (port of the kernel guid_t).
+struct guid_t {
+    std::uint8_t data[16];
+};
+
+inline auto load_le16(void const *p) -> std::uint16_t
+{
+    auto const b = static_cast<std::uint8_t const *>(p);
+    return static_cast<std::uint16_t>(b[0] | (b[1] << 8));
+}
+
+inline auto store_le16(void *p, std::uint16_t v) -> void
+{
+    auto *b = static_cast<std::uint8_t *>(p);
+    b[0] = static_cast<std::uint8_t>(v & 0xFF);
+    b[1] = static_cast<std::uint8_t>((v >> 8) & 0xFF);
+}
+
+inline auto load_le32(void const *p) -> std::uint32_t
+{
+    auto const b = static_cast<std::uint8_t const *>(p);
+    return static_cast<std::uint32_t>(
+        b[0] | (b[1] << 8) | (b[2] << 16) | (static_cast<std::uint32_t>(b[3]) << 24));
+}
+
+inline auto store_le32(void *p, std::uint32_t v) -> void
+{
+    auto *b = static_cast<std::uint8_t *>(p);
+    b[0] = static_cast<std::uint8_t>(v & 0xFF);
+    b[1] = static_cast<std::uint8_t>((v >> 8) & 0xFF);
+    b[2] = static_cast<std::uint8_t>((v >> 16) & 0xFF);
+    b[3] = static_cast<std::uint8_t>((v >> 24) & 0xFF);
+}
+
+} // namespace xone