fix(logo): pagina Logo RU agora usa logos oficiais RU

Era refs leftover do template STI (logo-sti-*.svg que nem existiam no RU3).
Agora referencia: brand-dark.svg, brand-light.svg, logo-ru-vertical.svg,
ru-ufpe.svg, logo-monochrome-horizontal-light.svg, vertical-light.svg.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>