MVP core recesso: App Proxy flow + ricevuta durevole + design storefront

- A1: SPEC-MVP-RECESSO.md (criteri + copy IT)
- A3: App Proxy /apps/recesso — lookup guest ordine+email (anti-leak), form 2-step,
  funzione dedicata Conferma recesso, persist WithdrawalRequest + transmittedAt + AuditLog
- A4: ricevuta durevole via nodemailer (mailer.server.ts) + receiptSentAt + AuditLog
- Design: recesso.server.ts restyle token CSS light/dark, coerente Shopify
- Fix: @shopify/shopify-api pinnato 13.1.0 (dedupe) -> tsc clean
- PLAN: A5 esteso a motore di stile a 3 livelli

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Mv83a29B4eFv5ixoj6PoE1

app/shopify.app.toml

@@ -6,6 +6,14 @@ name = "Legal Return PCRT "
 application_url = "https://miscellaneous-connections-harvest-chronicle.trycloudflare.com"
 embedded = true
 
+# App Proxy: lo storefront /apps/recesso viene proxato a <application_url>/proxy.
+# NB: se il tunnel Cloudflare (application_url) cambia, aggiornare anche `url` qui.
+# Richiede `shopify app deploy` perché la configurazione abbia effetto.
+[app_proxy]
+url = "https://miscellaneous-connections-harvest-chronicle.trycloudflare.com/proxy"
+subpath = "recesso"
+prefix = "apps"
+
 [build]
 automatically_update_urls_on_dev = false
 dev_store_url = "pcrt-reso-test.myshopify.com"