feat(tools): fw_info/fw_pack 镜像解析重打包（CRC32验证+字节级往返），112 测试全绿

tools/fw_pack.py

@@ -0,0 +1,11 @@
+#!/usr/bin/env python3
+"""fw_pack: 体→完整镜像（重算 CRC）。用法: fw_pack.py body.bin out.img [flags_hex]"""
+import sys
+from pathlib import Path
+from fw import pack_image
+
+if __name__ == "__main__":
+    body = Path(sys.argv[1]).read_bytes()
+    flags = int(sys.argv[3], 16) if len(sys.argv) > 3 else 0x01AA
+    Path(sys.argv[2]).write_bytes(pack_image(body, flags))
+    print(f"OK: {sys.argv[2]} ({len(body)}B body)")