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/repositories/file_repository.rs

@@ -12,7 +12,6 @@ use bytes::Bytes;
  * operations, providing detailed context for error handling across the application.
  */
 #[derive(Debug, thiserror::Error)]
-#[allow(dead_code)]
 pub enum FileRepositoryError {
     /// Returned when a requested file cannot be found by ID or path
     #[error("File not found: {0}")]
@@ -109,7 +108,6 @@ pub trait FileRepository: Send + Sync + 'static {
      * @param content Binary data of the file
      * @return The created File entity on success, error otherwise
      */
-    #[allow(dead_code)]
     async fn save_file_with_id(
         &self,
         id: String,
@@ -152,7 +150,6 @@ pub trait FileRepository: Send + Sync + 'static {
      * @param id The unique identifier of the file to delete
      * @return Success or error
      */
-    #[allow(dead_code)]
     async fn delete_file_entry(&self, id: &str) -> FileRepositoryResult<()>;
     
     /**