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/transactions/storage_transaction.rs

@@ -37,7 +37,6 @@ impl StorageTransaction {
     }
     
     /// Añade una operación sin rollback (para limpieza o logging)
-    #[allow(dead_code)]
     pub fn add_finalizer<F>(&mut self, finalizer: F)
     where
         F: Future<Output = Result<(), DomainError>> + Send + 'static,