fix(ci): 健壮化 Inno Setup 安装 + 部署仅保留最新安装包

- 新增 install-innosetup.ps1：校验下载大小、检查安装程序退出码、双
  Program Files 目录定位 ISCC，修复原内联命令静默成功但没真正装上的问题
  （SYSTEM 账户下 Invoke-WebRequest 无 -UseBasicParsing + 未检查退出码）
- provision/compile-windows.sh 在两个 Program Files 目录查找 ISCC
- deploy.sh 发布安装包到 /opt/jiu/downloads 前先清旧包，仅保留最新版本

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

scripts/ci/install-innosetup.ps1

@@ -0,0 +1,33 @@
+# install-innosetup.ps1 — robust silent install of Inno Setup 6 for the Windows runner.
+# Idempotent: exits 0 immediately if ISCC.exe is already present.
+$ErrorActionPreference = 'Stop'
+
+$candidates = @(
+  "${env:ProgramFiles(x86)}\Inno Setup 6\ISCC.exe",
+  "$env:ProgramFiles\Inno Setup 6\ISCC.exe"
+)
+foreach ($c in $candidates) {
+  if (Test-Path $c) { Write-Output "ISCC already present: $c"; exit 0 }
+}
+
+$url = 'https://jrsoftware.org/download.php/is.exe'
+$out = Join-Path $env:TEMP 'innosetup-installer.exe'
+
+Write-Output "Downloading Inno Setup: $url"
+[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
+# -UseBasicParsing avoids the IE-engine dependency that fails under the SYSTEM account.
+Invoke-WebRequest -Uri $url -OutFile $out -UseBasicParsing
+
+$size = (Get-Item $out).Length
+Write-Output "Downloaded $size bytes"
+if ($size -lt 1000000) { throw "Downloaded file too small ($size bytes) - not a valid installer" }
+
+Write-Output "Installing silently..."
+$p = Start-Process -FilePath $out -ArgumentList '/VERYSILENT','/SUPPRESSMSGBOXES','/NORESTART','/SP-','/NOICONS' -Wait -PassThru
+Write-Output "Installer exit code: $($p.ExitCode)"
+if ($p.ExitCode -ne 0) { throw "Inno Setup installer failed with exit code $($p.ExitCode)" }
+
+foreach ($c in $candidates) {
+  if (Test-Path $c) { Write-Output "ISCC installed: $c"; exit 0 }
+}
+throw "ISCC not found after install (looked in: $($candidates -join ', '))"