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-8.ts

@@ -0,0 +1,64 @@
+import type { Stage } from "../types"
+
+const decimalExercises = [
+  // Read/identify decimals
+  { q: "¿0.5 es lo mismo que?", correct: "0.50", wrong1: "0.05", wrong2: "5.0", emoji: "🔢" },
+  { q: "¿Cuánto es 1.25 + 0.25?", correct: "1.50", wrong1: "1.00", wrong2: "1.75", emoji: "➕" },
+  { q: "¿Cuánto es 2.5 - 1.3?", correct: "1.2", wrong1: "1.0", wrong2: "1.8", emoji: "➖" },
+  { q: "¿0.75 es igual a qué fracción?", correct: "3/4", wrong1: "1/4", wrong2: "1/2", emoji: "🥧" },
+  { q: "¿0.5 es igual a qué fracción?", correct: "1/2", wrong1: "1/3", wrong2: "1/4", emoji: "🥧" },
+  { q: "¿Cuál número es mayor: 1.5 o 1.25?", correct: "1.5", wrong1: "1.25", wrong2: "Son iguales", emoji: "📏" },
+  { q: "¿Cuánto es 3.2 + 1.8?", correct: "5.0", wrong1: "4.0", wrong2: "5.5", emoji: "➕" },
+  { q: "¿Cuánto es 4.75 - 2.25?", correct: "2.50", wrong1: "2.00", wrong2: "2.75", emoji: "➖" },
+  { q: "¿Cuántos decimales tiene 3.14?", correct: "2", wrong1: "1", wrong2: "3", emoji: "🔢" },
+  { q: "¿0.25 es igual a qué fracción?", correct: "1/4", wrong1: "1/2", wrong2: "3/4", emoji: "🥧" },
+  { q: "¿Cuál es mayor: 0.8 o 0.75?", correct: "0.8", wrong1: "0.75", wrong2: "Son iguales", emoji: "📏" },
+  { q: "¿Cuánto es 1.2 × 2?", correct: "2.4", wrong1: "2.2", wrong2: "2.8", emoji: "✖️" },
+  { q: "¿Cuánto es 3.0 ÷ 2?", correct: "1.5", wrong1: "1.0", wrong2: "2.0", emoji: "➗" },
+  { q: "¿0.20 es lo mismo que?", correct: "0.2", wrong1: "0.02", wrong2: "2.0", emoji: "🔢" },
+  { q: "Ordená de menor a mayor: 1.2, 1.02, 1.20", correct: "1.02, 1.2, 1.20", wrong1: "1.2, 1.02, 1.20", wrong2: "1.20, 1.2, 1.02", emoji: "📊" },
+  { q: "¿0.1 + 0.2 = ?", correct: "0.3", wrong1: "0.12", wrong2: "0.03", emoji: "➕" },
+  { q: "¿0.5 × 10 = ?", correct: "5", wrong1: "0.05", wrong2: "50", emoji: "✖️" },
+  { q: "¿0.25 + 0.75 = ?", correct: "1.0", wrong1: "0.50", wrong2: "1.5", emoji: "➕" },
+  { q: "¿Cómo se escribe cinco centésimos?", correct: "0.05", wrong1: "0.5", wrong2: "0.005", emoji: "✏️" },
+  { q: "¿1 ÷ 4 = ?", correct: "0.25", wrong1: "0.5", wrong2: "0.75", emoji: "➗" },
+  { q: "¿0.9 + 0.1 = ?", correct: "1.0", wrong1: "0.10", wrong2: "1.10", emoji: "➕" },
+  { q: "¿Cuánto es 2.5 × 2?", correct: "5.0", wrong1: "4.5", wrong2: "5.5", emoji: "✖️" },
+  { q: "¿0.75 - 0.25 = ?", correct: "0.50", wrong1: "0.25", wrong2: "0.75", emoji: "➖" },
+  { q: "¿1/2 escrito como decimal es?", correct: "0.5", wrong1: "0.25", wrong2: "0.75", emoji: "🔢" },
+  { q: "¿0.3 es mayor, menor o igual a 0.30?", correct: "Igual", wrong1: "Mayor", wrong2: "Menor", emoji: "📏" },
+]
+
+const exercises: any[] = []
+for (let i = 0; i < decimalExercises.length; i++) {
+  const e = decimalExercises[i]
+  exercises.push({
+    id: `seb8-dec-${i}`,
+    stage: 8,
+    skillCode: `decimal-${i}`,
+    type: "conciencia",
+    prerequisites: i === 0 ? [] : [exercises[i - 1].id],
+    content: {
+      instruction: e.q,
+      text: e.q,
+      audioText: e.q,
+      emoji: e.emoji,
+      options: [
+        { label: e.correct, correct: true, id: `c-${i}` },
+        { label: e.wrong1, correct: false, id: `w1-${i}` },
+        { label: e.wrong2, correct: false, id: `w2-${i}` },
+      ].sort(() => Math.random() - 0.5),
+    },
+    functionalContext: "Leer, comparar y operar con decimales usando material base-10 Montessori.",
+    errorType: "confusion-letra",
+  })
+}
+
+const stage: Stage = {
+  id: 8,
+  name: "Decimales",
+  description: "Leer, comparar y operar con decimales usando bloques base-10 como material concreto.",
+  exercises,
+}
+
+export default stage