v2.2: Verkaufsfertig-Fundament — Mollie/Payment-Abstraktion, MwSt/Grundpreis (PAngV), Versandzonen, Bestellmails (Listmonk/SMTP/Log), Feature-Flags

- payments.js: einheitliche createPayment/Webhook-Schnittstelle (Mollie Default, Stripe, Demo); Auto-Provider-Wahl; Mollie-REST + /api/payments/webhook (idempotent); Fake-Key => sauberer Demo-Fallback
- mailer.js: sendMail via Listmonk-Tx / SMTP (nodemailer) / Log-Fallback (email_log); gebrandete Bestellbestaetigung bei paid
- DACH: products.mwst + base_amount/base_unit/base_price_per (Grundpreis); Storefront/Warenkorb/Checkout/Erfolg/Admin mit MwSt-Ausweis + Versand-Transparenz; tax_cents/shipping_cents/country an Orders
- shipping_zones-Tabelle + CRUD + shippingFor(); Admin 'Versand'; serverseitige Versandberechnung in /api/checkout + /api/shipping-quote (Laenderwahl live)
- Feature-Flags (feature_*) + feature()-Helper; Admin Module-Toggles; Newsletter-Gating (Popup/Subscribe)
- Admin-API/Manifest/ai-admin.txt um shipping_zones erweitert; MCP list/upsert/delete_shipping; README/.env.example ergaenzt; Version 2.2.0

src/styles/global.css

@@ -93,6 +93,7 @@ p{margin:0 0 1rem}
 .prod-cat{font-size:12px;font-weight:600;letter-spacing:.06em;text-transform:uppercase;color:var(--faint)}
 .prod-name{font-family:var(--serif);font-size:18px;color:var(--ink);line-height:1.2}
 .prod-price{margin-top:auto;font-size:17px;font-weight:700;color:var(--ink);padding-top:8px}
+.prod-tax{font-size:11.5px;color:var(--faint,#8a8580);margin-top:2px;line-height:1.3}
 .soldout{font-size:12px;color:var(--accent);font-weight:600}
 
 /* product detail */