- New secubox-app-smtp-relay package with centralized SMTP config
- Shared library with send_mail(), send_html_mail(), send_text_mail()
- CLI: smtp-relayctl with status/test/send/configure/admin commands
- RPCD: 5 methods for LuCI integration
- LuCI settings page with mode selection and test button
- Modes: external (SMTP server), local (auto-detect mailserver), direct
- Migrated reporter and bandwidth-manager to use shared library
- Backwards-compatible fallback to legacy per-app config
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
