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/francesca-lectura/etapa-8.ts

@@ -0,0 +1,67 @@
+import type { Stage } from "../types"
+
+const synonymPairs = [
+  { word: "contento", synonym: "alegre" },
+  { word: "grande", synonym: "enorme" },
+  { word: "bonito", synonym: "hermoso" },
+  { word: "rápido", synonym: "veloz" },
+  { word: "pequeño", synonym: "chico" },
+  { word: "difícil", synonym: "complicado" },
+  { word: "fácil", synonym: "sencillo" },
+  { word: "importante", synonym: "valioso" },
+  { word: "triste", synonym: "apenado" },
+  { word: "cansado", synonym: "agotado" },
+  { word: "inteligente", synonym: "listo" },
+  { word: "valiente", synonym: "audaz" },
+  { word: "curioso", synonym: "preguntón" },
+  { word: "famoso", synonym: "conocido" },
+  { word: "enojado", synonym: "furioso" },
+  { word: "cariñoso", synonym: "afectuoso" },
+  { word: "orgulloso", synonym: "satisfecho" },
+  { word: "tranquilo", synonym: "calmado" },
+  { word: "divertido", synonym: "entretenido" },
+  { word: "antiguo", synonym: "viejo" },
+  { word: "nuevo", synonym: "reciente" },
+  { word: "oscuro", synonym: "sombrío" },
+  { word: "brillante", synonym: "radiante" },
+  { word: "fuerte", synonym: "resistente" },
+  { word: "amable", synonym: "gentil" },
+]
+
+const exercises: any[] = []
+let idx = 0
+
+// Part 1: eleccion — choose the synonym
+for (let i = 0; i < synonymPairs.length; i++) {
+  const p = synonymPairs[i]
+  const wrong = synonymPairs[(i + 1) % synonymPairs.length].synonym
+  exercises.push({
+    id: `fra8-sinonimo-${i}`,
+    stage: 8,
+    skillCode: `sinonimo-${i}`,
+    type: "eleccion",
+    prerequisites: idx === 0 ? [`fra7-inferencia-9`] : [exercises[idx - 1].id],
+    content: {
+      instruction: `¿Cuál es un sinónimo de "${p.word}"?`,
+      audioText: `Buscá un sinónimo de ${p.word}`,
+      emoji: "📖",
+      options: [
+        { label: p.synonym, correct: true, id: `c-${i}` },
+        { label: wrong, correct: false, id: `w1-${i}` },
+        { label: p.word, correct: false, id: `w2-${i}` },
+      ].sort(() => Math.random() - 0.5),
+    },
+    functionalContext: "Enriquecer léxico identificando sinónimos de palabras comunes.",
+    errorType: "confusion-letra",
+  })
+  idx++
+}
+
+const stage: Stage = {
+  id: 8,
+  name: "Vocabulario y sinónimos",
+  description: "Enriquecer el léxico identificando sinónimos de palabras cotidianas.",
+  exercises,
+}
+
+export default stage