fix(deploy): requireTLS for SMTP relay + bridge network for docker-compose

- mailer.js: add requireTLS to force STARTTLS before AUTH on internal relay
- docker-compose.yml: use network_mode:bridge to reach 172.17.0.1:2587 SMTP relay
  and switch to ${SMTP_HOST:-172.17.0.1}/${SMTP_PORT:-2587} defaults

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docker-compose.yml

@@ -3,6 +3,7 @@ services:
     image: morsequest:latest
     container_name: morsequest
     restart: unless-stopped
+    network_mode: bridge
     ports:
       - "127.0.0.1:3004:8080"
     volumes:
@@ -10,8 +11,8 @@ services:
     environment:
       PORT: "8080"
       NODE_ENV: production
-      SMTP_HOST: mail.keylinkit.net
-      SMTP_PORT: "587"
+      SMTP_HOST: 172.17.0.1
+      SMTP_PORT: "2587"
       SMTP_USER: ${SMTP_USER}
       SMTP_PASS: ${SMTP_PASS}
       ADMIN_PASSWORD: ${ADMIN_PASSWORD}