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

components/child/trazo-letra.tsx

@@ -122,6 +122,28 @@ export default function TrazoLetra({
       i: { sx: w * 0.5, sy: h * 0.2, ex: w * 0.5, ey: h * 0.8 },
       o: { sx: w * 0.3, sy: h * 0.3, ex: w * 0.6, ey: h * 0.6 },
       u: { sx: w * 0.3, sy: h * 0.3, ex: w * 0.7, ey: h * 0.5 },
+      // Consonants: generic top-to-bottom, left-to-right arrow
+      b: { sx: w * 0.3, sy: h * 0.3, ex: w * 0.7, ey: h * 0.7 },
+      c: { sx: w * 0.6, sy: h * 0.3, ex: w * 0.4, ey: h * 0.7 },
+      d: { sx: w * 0.3, sy: h * 0.3, ex: w * 0.7, ey: h * 0.7 },
+      f: { sx: w * 0.5, sy: h * 0.2, ex: w * 0.5, ey: h * 0.8 },
+      g: { sx: w * 0.6, sy: h * 0.3, ex: w * 0.4, ey: h * 0.7 },
+      h: { sx: w * 0.5, sy: h * 0.2, ex: w * 0.5, ey: h * 0.8 },
+      j: { sx: w * 0.5, sy: h * 0.2, ex: w * 0.5, ey: h * 0.8 },
+      k: { sx: w * 0.3, sy: h * 0.3, ex: w * 0.7, ey: h * 0.7 },
+      l: { sx: w * 0.5, sy: h * 0.2, ex: w * 0.5, ey: h * 0.8 },
+      m: { sx: w * 0.3, sy: h * 0.3, ex: w * 0.7, ey: h * 0.5 },
+      n: { sx: w * 0.3, sy: h * 0.3, ex: w * 0.7, ey: h * 0.5 },
+      p: { sx: w * 0.5, sy: h * 0.2, ex: w * 0.5, ey: h * 0.8 },
+      q: { sx: w * 0.6, sy: h * 0.3, ex: w * 0.4, ey: h * 0.7 },
+      r: { sx: w * 0.3, sy: h * 0.3, ex: w * 0.7, ey: h * 0.7 },
+      s: { sx: w * 0.3, sy: h * 0.3, ex: w * 0.7, ey: h * 0.7 },
+      t: { sx: w * 0.5, sy: h * 0.2, ex: w * 0.5, ey: h * 0.8 },
+      v: { sx: w * 0.3, sy: h * 0.3, ex: w * 0.7, ey: h * 0.7 },
+      w: { sx: w * 0.3, sy: h * 0.3, ex: w * 0.7, ey: h * 0.5 },
+      x: { sx: w * 0.3, sy: h * 0.3, ex: w * 0.7, ey: h * 0.7 },
+      y: { sx: w * 0.3, sy: h * 0.3, ex: w * 0.7, ey: h * 0.7 },
+      z: { sx: w * 0.3, sy: h * 0.3, ex: w * 0.7, ey: h * 0.5 },
     }
 
     const path = arrowPaths[l.toLowerCase()]