chore(docs): completar Fase 2 — requisitos y arquitectura

- Añade/actualiza `docs/requirements.md`, `docs/architecture.md`, `docs/api-integration.md`, `docs/data-model.md`
- Documenta criterios de aceptación y decisiones técnico-arquitectónicas
- Recomendación: añadir `docs/legal-considerations.md` (pendiente)

backend/tsconfig.json

@@ -0,0 +1,20 @@
+{
+  "compilerOptions": {
+    "target": "ES2020",
+    "module": "CommonJS",
+    "esModuleInterop": true,
+    "moduleResolution": "node",
+    "rootDir": "src",
+    "outDir": "dist",
+    "strict": true,
+    "skipLibCheck": true,
+    "resolveJsonModule": true,
+    "forceConsistentCasingInFileNames": true
+  },
+  "include": ["src/**/*", "tests/**/*"],
+  "exclude": ["node_modules", "dist"],
+  "metadata": {
+    "autor": "GitHub Copilot",
+    "ultima_actualizacion": "2026-02-07"
+  }
+}