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/domain/services/mod.rs

@@ -1,3 +1,5 @@
 pub mod i18n_service;
 pub mod path_service;
-pub mod auth_service;
+
+// NOTE: auth_service has been moved to infrastructure/services/jwt_service.rs
+// The functionality is now exposed through application/ports/auth_ports.rs (TokenServicePort)