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/infrastructure/repositories/folder_fs_repository.rs

@@ -10,7 +10,8 @@ use crate::domain::entities::folder::{Folder, FolderError};
 use crate::domain::repositories::folder_repository::{
     FolderRepository, FolderRepositoryError, FolderRepositoryResult
 };
-use crate::domain::services::path_service::{StoragePath, PathService};
+use crate::domain::services::path_service::StoragePath;
+use crate::infrastructure::services::path_service::PathService;
 // use crate::application::ports::outbound::IdMappingPort;
 use crate::infrastructure::services::id_mapping_service::{IdMappingService, IdMappingError};
 use crate::application::services::storage_mediator::StorageMediator;
@@ -51,7 +52,6 @@ impl FolderFsRepository {
     
     /// Creates a stub repository for initialization purposes
     /// This is used temporarily during dependency injection setup
-    #[allow(dead_code)]
     pub fn new_stub() -> Self {
         let root_path = PathBuf::from("/tmp");
         let path_service = Arc::new(PathService::new(root_path.clone()));