Add unified SecuBox header navigation to all 12 Network Modes views
for consistent portal integration when accessed from SecuBox Portal:
- overview.js, router.js, accesspoint.js, doublenat.js
- multiwan.js, relay.js, sniffer.js, travel.js
- vpnrelay.js, dmz.js, wizard.js, settings.js
Pattern: Wrap view content with secubox-page-wrapper and prepend
SbHeader.render() to hide LuCI sidebar when in portal context.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>