Fix login blank screen and progress persistence

- Fix authStore to persist user data, not just isAuthenticated
- Fix progressStore handling of undefined API responses
- Remove minimax.md documentation file
- All progress now properly saves to PostgreSQL
- Login flow working correctly

frontend/src/pages/modulos/index.ts

@@ -0,0 +1,4 @@
+export { Modulo1Page } from './Modulo1Page';
+export { Modulo2Page } from './Modulo2Page';
+export { Modulo3Page } from './Modulo3Page';
+export { Modulo4Page } from './Modulo4Page';