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/etapa-5.ts

@@ -0,0 +1,41 @@
+import type { Stage } from "../types"
+
+const TABLAS = [2, 5, 10] as const
+
+const exercises: any[] = []
+
+let idx = 0
+for (const t of TABLAS) {
+  for (let m = 1; m <= 10; m++) {
+    const correct = t * m
+    exercises.push({
+      id: `fra5-tabla${t}-${m}`,
+      stage: 5,
+      skillCode: `tabla-${t}-x-${m}`,
+      type: "eleccion",
+      prerequisites: idx === 0 ? [] : [exercises[idx - 1]?.id].filter(Boolean),
+      content: {
+        instruction: `¿Cuánto es ${t} × ${m}?`,
+        audioText: `${t} por ${m} es ${correct}`,
+        emoji: "🔢",
+        options: [
+          { label: String(correct), correct: true, id: String(correct) },
+          { label: String(correct + 1), correct: false, id: `w1-${idx}` },
+          { label: String(correct + t), correct: false, id: `w2-${idx}` },
+        ].sort(() => Math.random() - 0.5),
+      },
+      functionalContext: `Memorizar tabla del ${t} con método Montessori (tabla de Pythagore).`,
+      errorType: "confusion-letra",
+    })
+    idx++
+  }
+}
+
+const stage: Stage = {
+  id: 5,
+  name: "Tablas de multiplicar (2, 5, 10)",
+  description: "Memorizar las tablas de multiplicar del 2, 5 y 10 con material Montessori (tabla de Pythagore, cuentas doradas).",
+  exercises,
+}
+
+export default stage