Replace Helcim integration with WooCommerce Stripe

.env.example

@@ -51,9 +51,14 @@ BOOKSRUN_FTP_REMOTE_PATH=
 INGRAM_API_KEY=
 INGRAM_ACCOUNT_ID=
 
-# --- Payments (Helcim) ---
-HELCIM_API_TOKEN=
-HELCIM_ACCOUNT_ID=
+# --- Payments (official WooCommerce Stripe gateway) ---
+# Use test keys in dev/staging and live keys only in production. The deploy
+# writes these values to gitignored Docker secret files before configuring
+# the plugin. Webhook signing secret is optional but strongly recommended.
+STRIPE_MODE=test
+STRIPE_PUBLISHABLE_KEY=
+STRIPE_SECRET_KEY=
+STRIPE_WEBHOOK_SECRET=
 
 # --- Marketing ---
 MAILERLITE_API_KEY=