chore: add Windows build and service scripts

scripts/install-nssm-service.ps1

@@ -0,0 +1,32 @@
+param(
+  [string]$ServiceName = "LingmaIpcProxy",
+  [string]$BinaryPath = "",
+  [string]$Arguments = "--host 127.0.0.1 --port 8095 --session-mode auto",
+  [string]$WorkingDirectory = "",
+  [string]$NssmPath = "nssm.exe",
+  [string]$Description = "Lingma IPC proxy service"
+)
+
+$ErrorActionPreference = "Stop"
+
+$repoRoot = Split-Path -Parent $PSScriptRoot
+
+if ([string]::IsNullOrWhiteSpace($BinaryPath)) {
+  $BinaryPath = Join-Path $repoRoot "dist\lingma-ipc-proxy.exe"
+}
+if ([string]::IsNullOrWhiteSpace($WorkingDirectory)) {
+  $WorkingDirectory = $repoRoot
+}
+
+if (!(Test-Path $BinaryPath)) {
+  throw "Binary not found: $BinaryPath"
+}
+
+Write-Host "Installing NSSM service: $ServiceName"
+& $NssmPath install $ServiceName $BinaryPath $Arguments
+& $NssmPath set $ServiceName AppDirectory $WorkingDirectory
+& $NssmPath set $ServiceName Description $Description
+& $NssmPath set $ServiceName Start SERVICE_AUTO_START
+
+Write-Host "Service installed. Start with:"
+Write-Host "  $NssmPath start $ServiceName"