1、Makefile 与 CodeBlocks 编译单元对齐，补 make pack / BURN_KEY，增加 build.bat 与固件打包脚本

2、下载脚本同时生成无 Key / 带 Key 镜像，USB 默认烧无 Key，build.bat key 烧带 Key
3、配对超时从 60s 改为 120s
4、增加需求文档

tools/pack_firmware.bat

@@ -0,0 +1,12 @@
+@echo off
+chcp 65001 >nul
+cd /d "%~dp0"
+powershell -NoProfile -ExecutionPolicy Bypass -File "%~dp0pack_firmware.ps1"
+if errorlevel 1 (
+    echo.
+    echo pack failed.
+    pause
+    exit /b 1
+)
+echo.
+pause