feat(api): POST /api/recipes/[id]/view fuer View-Beacon

Body { profile_id } via zod validiert. FK-Violation (unbekanntes
Profil oder Rezept) wird zu 404 normalisiert. Erfolg liefert 204
ohne Body — fire-and-forget vom Client.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/routes/api/recipes/[id]/view/+server.ts

@@ -0,0 +1,30 @@
+import type { RequestHandler } from './$types';
+import { z } from 'zod';
+import { error } from '@sveltejs/kit';
+import { getDb } from '$lib/server/db';
+import { validateBody } from '$lib/server/api-helpers';
+import { recordView } from '$lib/server/recipes/views';
+
+const Schema = z.object({
+  profile_id: z.number().int().positive()
+});
+
+export const POST: RequestHandler = async ({ params, request }) => {
+  const recipeId = Number(params.id);
+  if (!Number.isInteger(recipeId) || recipeId <= 0) {
+    error(400, { message: 'Invalid recipe id' });
+  }
+  const body = validateBody(await request.json().catch(() => null), Schema);
+
+  try {
+    recordView(getDb(), body.profile_id, recipeId);
+  } catch (e) {
+    // FK violation (unknown profile or recipe) → 404
+    if (e instanceof Error && /FOREIGN KEY constraint failed/i.test(e.message)) {
+      error(404, { message: 'Recipe or profile not found' });
+    }
+    throw e;
+  }
+
+  return new Response(null, { status: 204 });
+};