Add graph viewer dev server launcher

scripts/Start-EpiphanyGraphViewerDevServer.ps1

@@ -0,0 +1,89 @@
+[CmdletBinding()]
+param(
+    [string]$BindHost = "127.0.0.1",
+    [int]$Port = 4177,
+    [switch]$Install,
+    [switch]$Detached,
+    [string]$LogDir
+)
+
+Set-StrictMode -Version Latest
+$ErrorActionPreference = "Stop"
+
+$scriptDir = Split-Path -Parent $MyInvocation.MyCommand.Path
+$repoRoot = (Resolve-Path (Join-Path $scriptDir "..")).Path
+$viewerDir = Join-Path $repoRoot "web\epiphany-graph-viewer"
+$packageJson = Join-Path $viewerDir "package.json"
+$nodeModulesDir = Join-Path $viewerDir "node_modules"
+
+if (-not (Test-Path $packageJson)) {
+    throw "Could not find viewer package at '$viewerDir'."
+}
+
+if ($Install -or -not (Test-Path $nodeModulesDir)) {
+    Write-Host "Installing viewer dependencies in $viewerDir ..." -ForegroundColor Cyan
+    Push-Location $viewerDir
+    try {
+        & npm.cmd install
+        if ($LASTEXITCODE -ne 0) {
+            throw "npm install failed with exit code $LASTEXITCODE."
+        }
+    }
+    finally {
+        Pop-Location
+    }
+}
+
+$npmArgs = @(
+    "run",
+    "dev",
+    "--",
+    "--host",
+    $BindHost,
+    "--port",
+    $Port.ToString()
+)
+
+if ($Detached) {
+    if ([string]::IsNullOrWhiteSpace($LogDir)) {
+        $LogDir = Join-Path $repoRoot "out\epiphany-graph-viewer"
+    }
+
+    New-Item -ItemType Directory -Force -Path $LogDir | Out-Null
+
+    $stdoutPath = Join-Path $LogDir "dev.stdout.log"
+    $stderrPath = Join-Path $LogDir "dev.stderr.log"
+
+    $process = Start-Process `
+        -FilePath "npm.cmd" `
+        -ArgumentList $npmArgs `
+        -WorkingDirectory $viewerDir `
+        -RedirectStandardOutput $stdoutPath `
+        -RedirectStandardError $stderrPath `
+        -PassThru `
+        -WindowStyle Hidden
+
+    Start-Sleep -Seconds 2
+
+    Write-Host "Started detached viewer dev server." -ForegroundColor Green
+    Write-Host "PID: $($process.Id)"
+    Write-Host "Host: http://$BindHost`:$Port/"
+    Write-Host "STDOUT: $stdoutPath"
+    Write-Host "STDERR: $stderrPath"
+    Write-Host "Poll with:"
+    Write-Host "  Get-Content '$stdoutPath' -Tail 40"
+    return
+}
+
+Write-Host "Starting viewer dev server in $viewerDir ..." -ForegroundColor Green
+Write-Host "URL: http://$BindHost`:$Port/"
+Push-Location $viewerDir
+try {
+    & npm.cmd @npmArgs
+    if ($LASTEXITCODE -ne 0) {
+        throw "npm run dev failed with exit code $LASTEXITCODE."
+    }
+}
+finally {
+    Pop-Location
+}