refactor: remove serde from domain entities for Clean Architecture compliance

- Remove Serialize/Deserialize from File, Folder, Session, User, Contact entities
- Create contact_persistence_dto.rs for JSONB persistence in infrastructure layer
- Update contact_pg_repository to use persistence DTOs
- Fix dependency on zip crate (downgrade from 7.2.0 to 2.1.0)
- Fix unused variable warnings in main.rs
- Move PathService import from domain to infrastructure
- Add missing fields to CoreServices and RepositoryServices
- Create proper service initialization in main.rs

Clean Architecture improvements:
- Domain layer no longer depends on serde framework
- Persistence concerns isolated to infrastructure layer
- TokenClaims in auth_service.rs is only exception (required for JWT)

src/application/dtos/calendar_dto.rs

@@ -1,6 +1,5 @@
 use serde::{Serialize, Deserialize};
 use chrono::{DateTime, Utc};
-use uuid::Uuid;
 use std::collections::HashMap;
 use crate::domain::entities::calendar::Calendar;
 use crate::domain::entities::calendar_event::CalendarEvent;

src/application/dtos/user_dto.rs

@@ -65,4 +65,13 @@ pub struct ChangePasswordDto {
 #[derive(Debug, Serialize, Deserialize)]
 pub struct RefreshTokenDto {
     pub refresh_token: String,
+}
+
+/// Datos del usuario autenticado actual (para uso en servicios de application)
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct CurrentUser {
+    pub id: String,
+    pub username: String,
+    pub email: String,
+    pub role: String,
 }