Add restic backup stack with daily systemd timer

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

vaultwarden/compose.yml

@@ -11,6 +11,7 @@ services:
       INVITATIONS_ALLOWED: "true"
       SHOW_PASSWORD_HINT: "false"
       SMTP_HOST: mailpit
+      SMTP_FROM: ${SMTP_FROM}
       SMTP_FROM_NAME: Vaultwarden
       SMTP_SECURITY: off
       SMTP_PORT: 1025