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/services/calendar_service.rs

@@ -1,14 +1,12 @@
 use std::sync::Arc;
 use async_trait::async_trait;
 use chrono::{DateTime, Utc};
-use uuid::Uuid;
 
 use crate::application::dtos::calendar_dto::{
     CalendarDto, CalendarEventDto, CreateCalendarDto, UpdateCalendarDto,
     CreateEventDto, UpdateEventDto, CreateEventICalDto
 };
 use crate::application::ports::calendar_ports::{CalendarStoragePort, CalendarUseCase};
-use crate::interfaces::middleware::auth::CurrentUser;
 use crate::common::errors::{DomainError, ErrorKind};
 
 pub struct CalendarService {