Enhance API functionality and security: Added rate limiting and domain validation across multiple API endpoints, improved error handling for missing or invalid parameters, and refactored email handling in contact form for better security and maintainability. Updated README.md with production build instructions and prerequisites.

scripts/run-build.ps1

@@ -0,0 +1,46 @@
+#Requires -Version 5.1
+<#
+.SYNOPSIS
+  Erstellt ein Production-Bundle unter dist/ (ohne Branch-Wechsel).
+#>
+[CmdletBinding()]
+param(
+    [switch]$InPlace
+)
+
+$ErrorActionPreference = "Stop"
+$Root = (Resolve-Path (Join-Path $PSScriptRoot "..")).Path
+$BuildDir = Join-Path $Root "scripts\build"
+
+function Resolve-NodeTool([string]$ToolName) {
+    $command = Get-Command $ToolName -ErrorAction SilentlyContinue
+    if ($command) { return $command.Source }
+
+    $candidates = @(
+        (Join-Path $env:ProgramFiles "nodejs\$ToolName.cmd"),
+        (Join-Path ${env:ProgramFiles(x86)} "nodejs\$ToolName.cmd")
+    )
+
+    foreach ($candidate in $candidates) {
+        if (Test-Path $candidate) { return $candidate }
+    }
+
+    return $null
+}
+
+$npm = Resolve-NodeTool "npm"
+if (-not $npm) {
+    throw "npm nicht gefunden. Bitte Node.js installieren."
+}
+
+Set-Location $BuildDir
+& $npm ci --no-fund --no-audit
+if ($LASTEXITCODE -ne 0) { exit $LASTEXITCODE }
+
+if ($InPlace) {
+    & $npm run build:in-place
+} else {
+    & $npm run build
+}
+
+exit $LASTEXITCODE