Add PyInstaller release workflow

tools/build-windows.ps1

@@ -0,0 +1,27 @@
+$ErrorActionPreference = 'Stop'
+
+Set-Location (Split-Path -Parent $PSScriptRoot)
+
+$python = Join-Path $PWD '.venv\Scripts\python.exe'
+if (-not (Test-Path $python)) {
+    python -m venv .venv
+}
+
+& $python -m pip install --upgrade pip
+& $python -m pip install -e '.[build]'
+
+& $python -m PyInstaller --clean --noconfirm 'packaging\NTE History Exporter.spec'
+if ($LASTEXITCODE -ne 0) {
+    throw "PyInstaller failed with exit code $LASTEXITCODE"
+}
+
+$exe = Join-Path $PWD 'dist\nte-history-exporter.exe'
+if (-not (Test-Path $exe)) {
+    throw "Expected build output was not created: $exe"
+}
+
+Write-Host "Built $exe"
+& $exe --help
+if ($LASTEXITCODE -ne 0) {
+    throw "Built executable smoke test failed with exit code $LASTEXITCODE"
+}