feat(docker): add Docker deployment configuration

Add production-ready Docker setup with multi-stage Dockerfile, docker-compose
orchestration for API, PostgreSQL, Redis, and Nginx services. Includes
health checks, non-root user execution, and proper networking.

- Add multi-stage Dockerfile with gunicorn/gevent workers
- Add docker-compose.yml with api, db, redis, nginx services
- Add nginx reverse proxy configuration with security headers
- Update .env.example with Docker and production variables
- Add email provider configuration (Mailgun, SendGrid)
- Add requests dependency for HTTP client support
- Update documentation with Docker deployment guide
- Rebrand project name from Gatehouse to Secuird

.env.example

@@ -2,8 +2,24 @@ FLASK_APP=manage.py
 FLASK_ENV=development
 FLASK_DEBUG=1
 
-# Database
-DATABASE_URL=postgresql://user:password@localhost:5432/gatehouse_dev
+# ═════════════════════════════════════════════════════════════════════════════
+# Docker / Production
+# ═════════════════════════════════════════════════════════════════════════════
+COMPOSE_PROJECT_NAME=authy2
+FLASK_ENV=production
+POSTGRES_USER=authy2
+POSTGRES_PASSWORD=changeme-in-production
+POSTGRES_DB=authy2
+DATABASE_URL=postgresql://${POSTGRES_USER}:${POSTGRES_PASSWORD}@db:5432/${POSTGRES_DB}
+SQLALCHEMY_DATABASE_URI=${DATABASE_URL}
+REDIS_URL=redis://redis:6379/0
+SESSION_REDIS_URL=redis://redis:6379/0
+RATELIMIT_STORAGE_URL=redis://redis:6379/1
+HTTP_PORT=80
+HTTPS_PORT=443
+API_PORT=5000
+
+# Database (overridden by Docker values above)
 SQLALCHEMY_ECHO=False
 SQLALCHEMY_LOG_LEVEL=WARNING
 
@@ -15,7 +31,7 @@ CA_ENCRYPTION_KEY=change-me-in-production
 BCRYPT_LOG_ROUNDS=12
 
 # Session cookies
-SESSION_COOKIE_SECURE=False
+SESSION_COOKIE_SECURE=True
 SESSION_COOKIE_SAMESITE=Lax
 # Only needed when sharing cookies across subdomains (e.g. api.example.com + ui.example.com)
 # SESSION_COOKIE_DOMAIN=example.com
@@ -61,7 +77,7 @@ OIDC_BASE_URL=http://localhost:5000
 # WebAuthn
 # ─────────────────────────────────────────────────────────────────────────────
 WEBAUTHN_RP_ID=localhost
-WEBAUTHN_RP_NAME=Gatehouse
+WEBAUTHN_RP_NAME=Secuird
 WEBAUTHN_ORIGIN=http://localhost:8080
 
 # ─────────────────────────────────────────────────────────────────────────────
@@ -81,6 +97,19 @@ SMTP_USERNAME=
 SMTP_PASSWORD=
 FROM_ADDRESS=noreply@gatehouse.local
 
+# Email Provider (smtp, mailgun, sendgrid)
+# Note: SMTP is the default. Set to "mailgun" or "sendgrid" to use those providers
+EMAIL_PROVIDER=smtp
+
+# Mailgun Configuration (used when EMAIL_PROVIDER=mailgun)
+# MAILGUN_API_KEY=your-mailgun-api-key
+# MAILGUN_DOMAIN=mg.yourdomain.com
+# MAILGUN_API_URL=https://api.mailgun.net/v3
+
+# SendGrid Configuration (used when EMAIL_PROVIDER=sendgrid)
+# SENDGRID_API_KEY=SG.your-sendgrid-api-key
+# SENDGRID_FROM_EMAIL=noreply@yourdomain.com
+
 # ─────────────────────────────────────────────────────────────────────────────
 # Logging
 # ─────────────────────────────────────────────────────────────────────────────