Replace BPS Excel stub with multi-client calendar template.

Official download now generates a blank workbook with catalog autofill, notas_internas ignored on import, and the same template for every tenant.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/app/api/calendar/upload/route.ts

@@ -9,11 +9,11 @@ import {
 } from '@/lib/agency';
 import {
   parseJsonCalendar,
-  SAMPLE_CSV,
   sheetsToPlans,
   type ImportResult,
   type SheetRows,
 } from '@/lib/calendar-import';
+import { buildOfficialCsv } from '@/lib/calendar-template';
 import type { RrssMonthPlan } from '@/components/RrssMonthView';
 
 export const dynamic = 'force-dynamic';
@@ -21,12 +21,14 @@ export const runtime = 'nodejs';
 
 const MAX_BYTES = 8 * 1024 * 1024;
 
+/** @deprecated Prefer GET /api/calendar/template?format=csv */
 export async function GET() {
-  return new NextResponse(SAMPLE_CSV, {
+  return new NextResponse(buildOfficialCsv('CLIENTE'), {
     headers: {
       'Content-Type': 'text/csv; charset=utf-8',
       'Content-Disposition':
         'attachment; filename="plantilla-calendario-4ventures.csv"',
+      'Cache-Control': 'no-store',
     },
   });
 }