ingestion: reject submissions containing disallowed phrases

/api/ai/submit and /api/submission-receive now scan incoming payload
title + body against the bb.disallowed_phrases allowlist (cached 3
min) and return 422 with the matching phrases if any are found. Stops
competitor mentions from re-entering the pipeline after the bulk
purge.

src/app/api/submission-receive/route.ts

@@ -1,5 +1,6 @@
 import { NextResponse, type NextRequest } from 'next/server';
 import { createClient } from '@supabase/supabase-js';
+import { findViolations } from '@/lib/disallowed-phrases-guard';
 
 export const dynamic = 'force-dynamic';
 
@@ -36,6 +37,17 @@ export async function POST(request: NextRequest) {
   const content = (body?.body || '').toString();
   if (!title || !content) return NextResponse.json({ error: 'title and body are required' }, { status: 400 });
 
+  // Editorial guardrail: reject anything mentioning a disallowed phrase
+  // (competitor publications, banned exhibitors, etc.) before it ever lands
+  // in bb.native_articles.
+  const violations = await findViolations(`${title}\n${content}`);
+  if (violations.length > 0) {
+    return NextResponse.json(
+      { error: 'Submission rejected: contains disallowed phrases', violations },
+      { status: 422 },
+    );
+  }
+
   const contributor = body?.contributor || {};
   const featuredImage = body?.featured_image_url || null;
   const attachments = Array.isArray(body?.attachments) ? body.attachments : [];