Panel Admin: pinned sidebar-first entry + emoji/numbered card grid

Elazar fleet spec (bs-mrlnhbp0y3n): every app's admin landing pinned as FIRST sidebar item, labeled 'Panel Admin', card grid with emoji per card, temp order numbers in +10 increments (10,20,30..) sorted asc, visible for now per Elazar 'temporarily'. Pluto: restyle-in-place on existing /admin/page.tsx (already has a card grid in the visibleSections array) + rename sidebar entry from 'Plataforma' (currently buried under Administrar section header) to 'Panel Admin' pinned first, gated on requireAnyCap(fullAccess,viewLogs,manageUsers,managePeriodos) same as the page itself. Convert sections array to ordered {order,emoji,label,href,cap} config, generalize the existing soporte-only cap-filter to per-card. KPI stats row above the cards stays as-is (data, not links) -- untouched.