feat: API Keys via Umgebungsvariablen konfigurierbar

- Neuer getApiKey() Helper: prüft zuerst ENV-Vars, dann DB
- Alle Job-Routes nutzen getApiKey() statt direktem DB-Lookup
- Credentials-Status berücksichtigt ENV-Vars (Sidebar-Haken)
- .env.local.example: Platzhalter für alle 4 API Keys

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/api/jobs/vayne-scrape/route.ts

@@ -1,6 +1,6 @@
 import { NextRequest, NextResponse } from "next/server";
 import { prisma } from "@/lib/db";
-import { decrypt } from "@/lib/utils/encryption";
+import { getApiKey } from "@/lib/utils/apiKey";
 import { createOrder, getOrderStatus, triggerExport, downloadOrderCSV } from "@/lib/services/vayne";
 
 export async function POST(req: NextRequest) {
@@ -12,11 +12,8 @@ export async function POST(req: NextRequest) {
       return NextResponse.json({ error: "Invalid Sales Navigator URL" }, { status: 400 });
     }
 
-    const cred = await prisma.apiCredential.findUnique({ where: { service: "vayne" } });
-    if (!cred?.value) {
-      return NextResponse.json({ error: "Vayne API token not configured" }, { status: 400 });
-    }
-    const apiToken = decrypt(cred.value);
+    const apiToken = await getApiKey("vayne");
+    if (!apiToken) return NextResponse.json({ error: "Vayne API token not configured" }, { status: 400 });
 
     const job = await prisma.job.create({
       data: {