feat: multi-profile system with Francesca and Sebastian curricula

- Add Profile enum (ISABELLA, FRANCESCA, SEBASTIAN) to Child model
- Add ?profile= query param override to /api/curriculum/next
- Pass profile prop from profile-specific pages to ExerciseSession
- Fix curriculum import paths (engine uses @/curriculum/ alias)
- Clear stale curriculumCache on dev reload
- Fix self-referential prerequisites in Francesca etapa-1
- Fix prerequisite chains in Francesca etapa-2,3,4 and Sebastian etapa-2,3
- Add Francesca curriculum: 2-3 digit sums, subtractions, multiplications, short readings
- Add Sebastian curriculum: 2-3 digit sums, interactive exercises, Argentine history, flags
- All 44 E2E tests pass, TypeScript compiles cleanly

curriculum/sebastian/etapa-1.ts

@@ -0,0 +1,92 @@
+import type { Stage } from '../types'
+
+const ejercicios = [
+  {
+    id: 'seb-suma-1',
+    content: {
+      instruction: 'Sumá: 15 + 27',
+      audioText: '15 más 27 es',
+      emoji: '➕',
+    },
+    options: [
+      { label: '42', correct: true, id: '42' },
+      { label: '40', correct: false, id: '40' },
+      { label: '45', correct: false, id: '45' },
+    ],
+  },
+  {
+    id: 'seb-suma-2',
+    content: {
+      instruction: 'Sumá: 34 + 56',
+      audioText: '34 más 56 es',
+      emoji: '➕',
+    },
+    options: [
+      { label: '90', correct: true, id: '90' },
+      { label: '80', correct: false, id: '80' },
+      { label: '100', correct: false, id: '100' },
+    ],
+  },
+  {
+    id: 'seb-suma-3',
+    content: {
+      instruction: 'Sumá: 78 + 22',
+      audioText: '78 más 22 es',
+      emoji: '➕',
+    },
+    options: [
+      { label: '100', correct: true, id: '100' },
+      { label: '99', correct: false, id: '99' },
+      { label: '101', correct: false, id: '101' },
+    ],
+  },
+  {
+    id: 'seb-suma-4',
+    content: {
+      instruction: 'Sumá: 45 + 55',
+      audioText: '45 más 55 es',
+      emoji: '➕',
+    },
+    options: [
+      { label: '100', correct: true, id: '100' },
+      { label: '95', correct: false, id: '95' },
+      { label: '110', correct: false, id: '110' },
+    ],
+  },
+  {
+    id: 'seb-suma-5',
+    content: {
+      instruction: 'Sumá: 123 + 456',
+      audioText: '123 más 456 es',
+      emoji: '➕',
+    },
+    options: [
+      { label: '579', correct: true, id: '579' },
+      { label: '569', correct: false, id: '569' },
+      { label: '580', correct: false, id: '580' },
+    ],
+  },
+]
+
+const exercises: any[] = []
+for (let i = 0; i < ejercicios.length; i++) {
+  const e = ejercicios[i]
+  exercises.push({
+    ...e,
+    stage: 1,
+    skillCode: `seb-suma-${i + 1}`,
+    type: 'eleccion',
+    prerequisites: i === 0 ? [] : [ejercicios[i - 1].id],
+    functionalContext: 'Sumas de 2-3 dígitos nivel inicial.',
+    errorType: 'discriminacion-auditiva',
+  })
+}
+
+const stage: Stage = {
+  id: 1,
+  name: 'Sumas 2-3 dígitos',
+  description: 'Resolver sumas de 2 y 3 dígitos de forma fluida.',
+  exercises,
+}
+
+export default stage