feat: port MT76 firmware load and download script

Add chip::load_firmware(): validates the xow_dongle.bin header, DMAs
the ILM and DLM images in 0x3800-byte chunks over EP 0x04 OUT with
FCE completion polling, then loads the IVB and waits for the firmware
to start. Probe now issues a USB reset first (port of
usb_reset_device), matching xone_dongle_probe.

The chip keeps its firmware across a USB reset on macOS and does not
set the upstream reset-complete bit, so load_firmware falls back to
the running firmware when the chip is still alive. Verified on
hardware: fresh load and re-plug both return success.

Add scripts/download-firmware.sh (port of install/firmware.sh), which
fetches the driver CAB from Windows Update and extracts
firmware/xow_dongle.bin, hash-verified.

Co-Authored-By: qwen3.8-27b@q2_k_xl: ported firmware load and download script

CMakeLists.txt

@@ -6,7 +6,7 @@ if(NOT CMAKE_GENERATOR MATCHES "^(Ninja|Xcode)$")
 endif()
 
 cmake_minimum_required(VERSION 3.21)
-project(xone_macos VERSION 0.1.5 LANGUAGES CXX Swift)
+project(xone_macos VERSION 0.1.6 LANGUAGES CXX Swift)
 
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)