fix: switch to port 587 with STARTTLS for IONOS SMTP

Port 465 with implicit SSL is not working. Switching to port 587
with STARTTLS (SMTP_TLS: always) which is more compatible with
Swoosh SMTP adapter.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

asciinema/compose.yaml

@@ -15,15 +15,12 @@ services:
       URL_SCHEME: https
       DATABASE_URL: postgresql://${DB_USER}:${DB_PASSWORD}@${CORE_DB_HOST}/${ASCIINEMA_DB_NAME}?pool_size=10
       SMTP_HOST: ${EMAIL_SMTP_HOST}
-      SMTP_PORT: ${EMAIL_SMTP_PORT}
+      SMTP_PORT: 587
       SMTP_USERNAME: ${EMAIL_SMTP_USER}
       SMTP_PASSWORD: ${EMAIL_SMTP_PASSWORD}
-      SMTP_TLS: never
-      SMTP_SSL: true
+      SMTP_TLS: always
       SMTP_AUTH: always
-      SMTP_NO_MX_LOOKUPS: true
-      SMTP_TLS_VERIFY_HOST: false
-      SMTP_TLS_VERIFY_CERT: false
+      SMTP_RETRIES: 2
       MAIL_FROM_ADDRESS: ${EMAIL_FROM}
       MAIL_REPLY_TO_ADDRESS: ${ASCIINEMA_MAIL_REPLY_TO}
       SIGN_UP_DISABLED: ${ASCIINEMA_SIGN_UP_DISABLED:-false}