feat: integrate Resend for OTP email delivery and update configuration

README.md

@@ -37,7 +37,7 @@ has been built.
 Local seeded admin:
 
 - email: `[email protected]`
-- access uses OTP through Mailpit and is for local development only.
+- access uses OTP email delivery and needs mail provider config.
 
 If you already had a MySQL volume from the old scaffold, create the local
 database/user once:
@@ -93,6 +93,21 @@ python3 -m unittest scripts/test_generate_openapi.py
 The app serves the generated JSON at `/api/v1/openapi.json` and Swagger UI at
 `/api/v1/docs`.
 
+## Email Delivery
+
+OTP delivery uses Resend HTTP API through Drogon's async `HttpClient`.
+Set these environment variables before starting backend:
+
+```bash
+export MAIL_PROVIDER=resend
+export RESEND_API_BASE_URL=https://api.resend.com
+export RESEND_API_KEY=re_xxx
+export MAIL_FROM=[email protected]
+```
+
+Mailpit can still run locally for manual inspection or future integrations, but
+current backend OTP flow no longer speaks SMTP directly.
+
 ## Visione Lab
 
 `scripts/lab/` is a small Streamlit frontend used only to test the backend
@@ -137,11 +152,12 @@ backend deployment with MySQL and a local SMTP catcher. Configure the public
 domain in Dokploy against service `backend` and container port `5555`.
 
 The runtime image includes `config.json`; override environment-specific values
-with Dokploy environment variables. The SMTP catcher service uses the
+with Dokploy environment variables. The Mailpit service uses the
 multi-architecture Mailpit image to avoid `exec format error` failures on ARM
 servers.
 
-Set `DB_NAME`, `DB_USER`, `DB_PASSWORD`, `MYSQL_ROOT_PASSWORD` and
+Set `DB_NAME`, `DB_USER`, `DB_PASSWORD`, `MYSQL_ROOT_PASSWORD`,
+`RESEND_API_KEY`, `MAIL_FROM` and
 `CORS_ALLOWED_ORIGIN` in Dokploy environment variables. Use the exact browser
 origin without quotes or a trailing slash, for example
 `https://visione.studentindipendenti.it`.