feat: интерактивный установщик install.sh (Docker / Ubuntu, админ, БД)

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

src/seed-promo.js

@@ -0,0 +1,20 @@
+const { query } = require('./db');
+
+async function seedPromoCodes() {
+  const { rows } = await query('SELECT COUNT(*)::int AS n FROM promo_codes');
+  if (rows[0].n > 0) return;
+
+  const expires = new Date();
+  expires.setDate(expires.getDate() + 30);
+
+  await query(
+    `INSERT INTO promo_codes (code, description, discount_type, discount_value, expires_at, min_order_cents)
+     VALUES
+       ('WELCOME10', 'Скидка 10% новым покупателям', 'percent', 10, $1, 0),
+       ('SALE500', 'Скидка 500 ₽ от 3000 ₽', 'fixed', 50000, $1, 300000)`,
+    [expires.toISOString()]
+  );
+  console.log('Демо-промокоды: WELCOME10, SALE500');
+}
+
+module.exports = { seedPromoCodes };