feat: export a import kampani a cenoviek pre prenos na novy server

- npm run db:export: kampane a sablony cenoviek do supabase/data/ (+ obrazky z uloziska)
- npm run db:import [-- --dry-run]: nahra data s povodnymi ID, prepise odkazy
  na nove ulozisko, da sa spustit opakovane
- aktualny export: 7 kampani, 1 sablona cenovky

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

scripts/export-data.mjs

@@ -0,0 +1,69 @@
+// Export kampaní (templates) a šablón cenoviek (badges) zo Supabase do supabase/data/
+// pre prenos na nový server. Stiahne aj obrázky z úložiska newsletter-assets, na ktoré
+// dáta odkazujú a nie sú medzi statickými obrázkami v supabase/assets/.
+// Spustenie: npm run db:export   (číta .env.local pôvodného projektu)
+import { createClient } from '@supabase/supabase-js';
+import { mkdir, writeFile, access } from 'node:fs/promises';
+import path from 'node:path';
+
+const BUCKET = 'newsletter-assets';
+const TABLES = ['templates', 'badges'];
+const DATA_DIR = path.join(process.cwd(), 'supabase', 'data');
+const FILES_DIR = path.join(DATA_DIR, 'files');
+const ASSETS_DIR = path.join(process.cwd(), 'supabase', 'assets');
+
+const url = (process.env.NEXT_PUBLIC_SUPABASE_URL || '').replace(/\/$/, '');
+const key = process.env.SUPABASE_SERVICE_ROLE_KEY || process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY;
+if (!url || !key) {
+  console.error('Chýba NEXT_PUBLIC_SUPABASE_URL alebo kľúč (SUPABASE_SERVICE_ROLE_KEY / NEXT_PUBLIC_SUPABASE_ANON_KEY) v .env.local');
+  process.exit(1);
+}
+
+const supabase = createClient(url, key);
+const storageBase = `${url}/storage/v1/object/public/${BUCKET}/`;
+await mkdir(FILES_DIR, { recursive: true });
+
+const referenced = new Set();
+for (const table of TABLES) {
+  const { data, error } = await supabase.from(table).select('*').order('created_at', { ascending: true });
+  if (error) {
+    console.error(`✗ ${table}: ${error.message}`);
+    process.exit(1);
+  }
+  await writeFile(path.join(DATA_DIR, `${table}.json`), JSON.stringify(data, null, 2) + '\n');
+  console.log(`✓ ${table}: ${data.length} záznamov`);
+
+  // Odkazy na súbory v úložisku (cesta v rámci bucketu)
+  const json = JSON.stringify(data);
+  let i = 0;
+  while ((i = json.indexOf(storageBase, i)) !== -1) {
+    const start = i + storageBase.length;
+    let end = start;
+    while (end < json.length && !`"'()\\ `.includes(json[end])) end++;
+    referenced.add(decodeURIComponent(json.slice(start, end)));
+    i = end;
+  }
+}
+
+const exists = (p) => access(p).then(() => true, () => false);
+let downloaded = 0;
+for (const filePath of referenced) {
+  // Statické obrázky šablóny sú už v supabase/assets a nahrajú sa cez db:upload-assets
+  if (!filePath.includes('/') && (await exists(path.join(ASSETS_DIR, filePath)))) continue;
+  const res = await fetch(storageBase + filePath.split('/').map(encodeURIComponent).join('/'));
+  if (!res.ok) {
+    console.warn(`! ${filePath}: HTTP ${res.status} (preskočené)`);
+    continue;
+  }
+  const target = path.join(FILES_DIR, filePath);
+  await mkdir(path.dirname(target), { recursive: true });
+  await writeFile(target, Buffer.from(await res.arrayBuffer()));
+  downloaded++;
+}
+
+await writeFile(
+  path.join(DATA_DIR, 'meta.json'),
+  JSON.stringify({ exportedAt: new Date().toISOString(), sourceStorageBase: storageBase }, null, 2) + '\n'
+);
+console.log(`✓ obrázky: ${referenced.size} odkazov, ${downloaded} stiahnutých do supabase/data/files/`);
+console.log('\nHotovo. Commitnite priečinok supabase/data/ a na novom serveri spustite npm run db:import.');