SOP-MARS-66: lector grant inert when user also holds ayudante

Ferley Rios Jimenez (user 5067d729-dd6e-4b7c-9191-930485113184) was granted lector on 2026-09-22 15:59Z for SOP-MARS-60 (research access to grado 4th-year practicas for Dra Ciolli's study). He came back on SOP-MARS-66 asking for news because the grant does nothing for him. Cause: src/app/(protected)/practicas/page.tsx sets isReadOnlyAll = !viewStudents && viewAllPracticas, so hasGlobalScope is false for anyone who ALSO holds a teaching role. He holds ayudante (viewStudents) + alumno + lector, so getScopedPracticas runs with fullAccess:false and he sees only his own comisiones. /practicas/[id] honours viewAllPracticas correctly, so direct links work while the list does not. Fix belongs to coder-mars-cc: hasGlobalScope should derive from the capability, not from the absence of other roles.