refactor: abstract site URL across email templates

- Add NEXT_PUBLIC_SITE_URL to .env.local
- Update email templates to accept siteUrl prop
- Update webhook handler to pass siteUrl from env var
- Update create-webhooks.graphql with placeholder URL

src/emails/OrderConfirmation.tsx

@@ -17,6 +17,7 @@ interface OrderConfirmationProps {
   items: OrderItem[];
   total: string;
   shippingAddress?: string;
+  siteUrl: string;
 }
 
 const translations: Record<
@@ -101,11 +102,12 @@ export function OrderConfirmation({
   items,
   total,
   shippingAddress,
+  siteUrl,
 }: OrderConfirmationProps) {
   const t = translations[language] || translations.en;
 
   return (
-    <BaseLayout previewText={t.preview} language={language}>
+    <BaseLayout previewText={t.preview} language={language} siteUrl={siteUrl}>
       <Text style={styles.title}>{t.title}</Text>
       <Text style={styles.greeting}>{t.greeting.replace("{name}", customerName)}</Text>
       <Text style={styles.text}>{t.orderReceived}</Text>
@@ -142,7 +144,7 @@ export function OrderConfirmation({
       )}
 
       <Section style={styles.buttonSection}>
-        <Button href="https://manoonoils.com" style={styles.button}>
+        <Button href={siteUrl} style={styles.button}>
           {language === "sr"
             ? "Pogledajte narudžbinu"
             : language === "de"