Archive flashable cyd_28r firmware bins for offline reflash.

Add flash scripts and export helper so the board can be programmed without rebuilding from source.

Co-authored-by: Cursor <cursoragent@cursor.com>

README.md

@@ -31,6 +31,18 @@ pio run -e cyd_28r -t upload
 pio device monitor -b 115200
 ```
 
+### 预编译固件（随时刷，不必编译）
+
+已归档到 [`firmware/cyd_28r/`](firmware/cyd_28r/)（含 bootloader / partitions / app）：
+
+```powershell
+cd firmware\cyd_28r
+.\flash.ps1
+# 或 .\flash.ps1 -Port COM3
+```
+
+说明见 [`firmware/README.md`](firmware/README.md)。源码更新后重新打包：`.\firmware\export_from_build.ps1`。
+
 ### 环境选择
 
 | 环境 | 适用 |
@@ -66,6 +78,7 @@ platformio.ini                 # 板级与库依赖
 include/lv_conf.h              # LVGL 配置
 src/main.cpp                   # 仪表盘主程序
 scripts/exclude_lvgl_asm.py    # 排除 ESP32 不兼容的 LVGL ASM
+firmware/                      # 预编译固件（可离线刷写）
 cad/                           # 3D 外壳（OpenSCAD + STL）
 .cursor/rules/                 # Cursor 协作规则
 README.md                      # 本文档
@@ -123,3 +136,4 @@ git reset --hard v1.1-case-snaps
 | 2026-10-17 | 打标签 `v1.1-case-snaps`（及分支 `keep/v1.1-case-snaps`）作为可回滚稳定版 |
 | 2026-10-17 | UI 重排：修文字压图表；表盘/底栏分区；动画与短按/长按交互 |
 | 2026-10-17 | 顶栏改单行，避免 up 文案被表盘面板盖住 |
+| 2026-10-17 | 归档预编译固件到 `firmware/cyd_28r/`，附一键刷写脚本 |