fix(build): 署名自检改用 Node 字节比对（findstr 在 chcp 65001 下匹配不了 UTF-8 中文）

findstr 会误报 NOT found，而实测 exe 里署名是存在的。改成 verify-signature.mjs
读字节 includes 比对，缺失时让构建硬失败。

deploy/build.bat

@@ -39,7 +39,7 @@ if exist "..\deploy\signature.build.txt" for /f "usebackq delims= eol=" %%A in (
 if defined INTERNAL_SIGNATURE (
   REM single quotes keep spaces inside the value intact for go's ldflags parser
   go build -ldflags "-X 'git.yeij.top/AskaEth/Scoreboard/server/internal/version.InternalSignature=%INTERNAL_SIGNATURE%'" -o ..\dist\scoreboard.exe . || exit /b 1
-  findstr /m /c:"%INTERNAL_SIGNATURE%" ..\dist\scoreboard.exe >nul || echo   [warn] signature NOT found in exe
+  node ..\deploy\verify-signature.mjs || exit /b 1
   echo   internal signature injected
 ) else (
   go build -o ..\dist\scoreboard.exe . || exit /b 1