choice: { type:"choice", q:"…", options:["A","B"], answer:0 }
multi: { type:"multi", q:"…", options:["A","B","C"], answers:[0,2] }
fill: { type:"fill", q:"…______…", accept:["resp"] } — Usa varios ______ con accept:["r1","r2"] para múltiples huecos
code: { type:"code", q:"…", code:"print(1)", accept:["1"] }
match: { type:"match", q:"…", pairs:[["Izq","Der"]], distractors:["extra"] }
array_click: { type:"array_click", q:"…", items:[1,2,3], lo:0, hi:2, answer_index:1 }
stack_visual: { type:"stack_visual", q:"…", code:"…", max_size:8, options:[{items:["a","b"],top:1}], answer:0 }