Sub-ticket of MARS-36 Implement sidebar regroup from /sidebars-preview (Elazar 06-06): adopt the previewed per-role nav as the LIVE app-sidebar, preserving MARS-33/34 /practicas changes (merged Prácticas, no Por-calificar link, Nueva-práctica as button). Shares app-sidebar.tsx with MARS-34 -> coder-mars owns, sequence AFTER MARS-34. coderhelp to define concrete current->proposed diff first. · mars