feat: fase 2+3 — expansion masiva multi-perfil + bug fixes + hardening

Fase 2 (expansion):
- Francesca: +6 etapas matematicas (5-10), +7 etapas lectura (3-9), +2 ortografia
- Sebastian: +8 etapas matematicas (4-11), +6 lectura, +3 historia, +3 geografia, +1 banderas
- Nuevas paginas: ortografia, lectura, geografia, matematicas
- ~900 ejercicios nuevos, paridad ~500 por perfil

Fase 3 (bug fixes + hardening):
- Fix: SessionLog auto-create en grade route
- Fix: engine cache (no borrar antes de revisar)
- Fix: FSRS cards actualizadas en flujo curriculum
- Fix: responseMs real (no hardcodeado 3000)
- Fix: options dentro de content en sebastian etapa-1
- Fix: trazo-letra consonantes crash
- Security: execFileSync anti-command-injection en TTS
- DB: 18 cascade deletes + indices + unique constraints
- APIs debug: reset, state, seed
- Docker: espeak-ng + prisma + user/group
- E2E: 23 tests nuevos (curriculum-flow.spec.ts)
- Code review: tailwind colors, middleware dev mode, eslint config

Verificado: tsc exit 0, build exit 0, 61 E2E tests pass

curriculum/sebastian/etapa-7.ts

@@ -0,0 +1,102 @@
+import type { Stage } from "../types"
+
+// Equivalences: 1/2 = 2/4 = 3/6, 1/3 = 2/6, 1/4 = 2/8
+const equivalencias: { a: string; b: string; result: boolean }[] = [
+  { a: "1/2", b: "2/4", result: true },
+  { a: "1/2", b: "3/6", result: true },
+  { a: "1/3", b: "2/6", result: true },
+  { a: "1/4", b: "2/8", result: true },
+  { a: "3/4", b: "6/8", result: true },
+  { a: "2/3", b: "4/6", result: true },
+  { a: "1/2", b: "2/3", result: false },
+  { a: "1/3", b: "1/4", result: false },
+  { a: "1/4", b: "1/2", result: false },
+  { a: "3/4", b: "1/2", result: false },
+  { a: "2/3", b: "3/4", result: false },
+  { a: "1/2", b: "1/3", result: false },
+  { a: "2/4", b: "3/6", result: true },
+  { a: "1/3", b: "3/9", result: true },
+  { a: "1/4", b: "3/12", result: true },
+]
+
+// Sumas y restas del mismo denominador
+const opFracs: { numA: number; den: number; numB: number; op: "+" | "-"; resultado: string }[] = [
+  { numA: 1, den: 4, numB: 2, op: "+", resultado: "3/4" },
+  { numA: 2, den: 5, numB: 1, op: "+", resultado: "3/5" },
+  { numA: 3, den: 8, numB: 2, op: "+", resultado: "5/8" },
+  { numA: 1, den: 3, numB: 1, op: "+", resultado: "2/3" },
+  { numA: 2, den: 7, numB: 3, op: "+", resultado: "5/7" },
+  { numA: 3, den: 4, numB: 1, op: "-", resultado: "2/4" },
+  { numA: 4, den: 5, numB: 1, op: "-", resultado: "3/5" },
+  { numA: 5, den: 8, numB: 2, op: "-", resultado: "3/8" },
+  { numA: 2, den: 3, numB: 1, op: "-", resultado: "1/3" },
+  { numA: 6, den: 7, numB: 2, op: "-", resultado: "4/7" },
+  { numA: 1, den: 6, numB: 2, op: "+", resultado: "3/6" },
+  { numA: 3, den: 10, numB: 4, op: "+", resultado: "7/10" },
+  { numA: 7, den: 9, numB: 2, op: "-", resultado: "5/9" },
+  { numA: 5, den: 6, numB: 1, op: "-", resultado: "4/6" },
+  { numA: 2, den: 9, numB: 5, op: "+", resultado: "7/9" },
+]
+
+const exercises: any[] = []
+let idx = 0
+
+// Part 1: equivalence recognition (conciencia)
+for (const eq of equivalencias) {
+  exercises.push({
+    id: `seb7-frac-eq-${idx}`,
+    stage: 7,
+    skillCode: `frac-eq-${idx}`,
+    type: "conciencia",
+    prerequisites: idx === 0 ? [] : [exercises[idx - 1].id],
+    content: {
+      instruction: eq.result
+        ? `¿${eq.a} es equivalente a ${eq.b}?`
+        : `¿${eq.a} es equivalente a ${eq.b}?`,
+      audioText: `${eq.a} es equivalente a ${eq.b}?`,
+      emoji: "🥧",
+      options: [
+        { label: "Verdadero", correct: eq.result, id: `true-${idx}` },
+        { label: "Falso", correct: !eq.result, id: `false-${idx}` },
+      ],
+    },
+    functionalContext: "Reconocer equivalencias entre fracciones con círculos Montessori.",
+    errorType: "confusion-letra",
+  })
+  idx++
+}
+
+// Part 2: addition/subtraction (eleccion)
+for (const op of opFracs) {
+  const wrong1 = `${op.numA + op.numB + 1}/${op.den}`
+  const wrong2 = `${Math.abs(op.numA - op.numB + op.den)}/${op.den}`
+  exercises.push({
+    id: `seb7-frac-op-${idx}`,
+    stage: 7,
+    skillCode: `frac-op-${idx}`,
+    type: "eleccion",
+    prerequisites: [exercises[idx - 1].id],
+    content: {
+      instruction: `Resolvé: ${op.numA}/${op.den} ${op.op} ${op.numB}/${op.den}`,
+      audioText: `${op.numA} ${op.op === "+" ? "más" : "menos"} ${op.numB}, sobre ${op.den}`,
+      emoji: "🧮",
+      options: [
+        { label: op.resultado, correct: true, id: `c-${idx}` },
+        { label: wrong1, correct: false, id: `w1-${idx}` },
+        { label: wrong2, correct: false, id: `w2-${idx}` },
+      ].sort(() => Math.random() - 0.5),
+    },
+    functionalContext: "Sumar y restar fracciones con el mismo denominador usando círculos Montessori.",
+    errorType: "confusion-letra",
+  })
+  idx++
+}
+
+const stage: Stage = {
+  id: 7,
+  name: "Fracciones: equivalencias y operaciones",
+  description: "Reconocer fracciones equivalentes y sumar/restar fracciones con el mismo denominador.",
+  exercises,
+}
+
+export default stage