feat: add test digest mode (?test=true) + group company sees all entries

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

src/app/api/notifications/digest/route.ts

@@ -1,11 +1,15 @@
 import { NextResponse } from "next/server";
 import { runDigest } from "@/core/notifications";
+import { sendTestDigest } from "@/core/notifications/notification-service";
 
 /**
  * POST /api/notifications/digest
  *
  * Server-to-server endpoint called by N8N cron.
  * Auth via Authorization: Bearer <NOTIFICATION_CRON_SECRET>
+ *
+ * Query params:
+ *   ?test=true — send a test email with sample data to all subscribers
  */
 export async function POST(request: Request) {
   const secret = process.env.NOTIFICATION_CRON_SECRET;
@@ -24,7 +28,10 @@ export async function POST(request: Request) {
     return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
   }
 
-  const result = await runDigest();
+  const url = new URL(request.url);
+  const isTest = url.searchParams.get("test") === "true";
+
+  const result = isTest ? await sendTestDigest() : await runDigest();
 
   return NextResponse.json(result, {
     status: result.success ? 200 : 500,