perf: replace dyn trait objects with concrete types to eliminate vtable overhead

Remove async-trait dependency and use native Rust async fn in traits.
Replace Arc<dyn Trait> with Arc<ConcreteType> throughout the codebase
to enable monomorphization and eliminate dynamic dispatch overhead.

Key changes:
- Remove write-behind cache (no implementation existed)
- Fix should_transcode static method call
- Use ContactStorageAdapter directly instead of dyn AddressBookUseCase
- Clean up unused trait imports across services and DI

https://claude.ai/code/session_01EbAFEfyJNLRmJHmmYDX3Tt

src/application/services/file_use_case_factory.rs

@@ -1,24 +1,23 @@
 use std::sync::Arc;
 
-use crate::application::ports::file_ports::{
-    FileManagementUseCase, FileRetrievalUseCase, FileUploadUseCase, FileUseCaseFactory,
-};
-use crate::application::ports::storage_ports::{FileReadPort, FileWritePort};
+use crate::application::ports::file_ports::FileUseCaseFactory;
 use crate::application::services::file_management_service::FileManagementService;
 use crate::application::services::file_retrieval_service::FileRetrievalService;
 use crate::application::services::file_upload_service::FileUploadService;
+use crate::infrastructure::repositories::pg::file_blob_read_repository::FileBlobReadRepository;
+use crate::infrastructure::repositories::pg::file_blob_write_repository::FileBlobWriteRepository;
 
 /// Factory for creating file use case implementations
 pub struct AppFileUseCaseFactory {
-    file_read_repository: Arc<dyn FileReadPort>,
-    file_write_repository: Arc<dyn FileWritePort>,
+    file_read_repository: Arc<FileBlobReadRepository>,
+    file_write_repository: Arc<FileBlobWriteRepository>,
 }
 
 impl AppFileUseCaseFactory {
     /// Creates a new factory for file use cases
     pub fn new(
-        file_read_repository: Arc<dyn FileReadPort>,
-        file_write_repository: Arc<dyn FileWritePort>,
+        file_read_repository: Arc<FileBlobReadRepository>,
+        file_write_repository: Arc<FileBlobWriteRepository>,
     ) -> Self {
         Self {
             file_read_repository,
@@ -28,15 +27,15 @@ impl AppFileUseCaseFactory {
 }
 
 impl FileUseCaseFactory for AppFileUseCaseFactory {
-    fn create_file_upload_use_case(&self) -> Arc<dyn FileUploadUseCase> {
+    fn create_file_upload_use_case(&self) -> Arc<FileUploadService> {
         Arc::new(FileUploadService::new(self.file_write_repository.clone()))
     }
 
-    fn create_file_retrieval_use_case(&self) -> Arc<dyn FileRetrievalUseCase> {
+    fn create_file_retrieval_use_case(&self) -> Arc<FileRetrievalService> {
         Arc::new(FileRetrievalService::new(self.file_read_repository.clone()))
     }
 
-    fn create_file_management_use_case(&self) -> Arc<dyn FileManagementUseCase> {
+    fn create_file_management_use_case(&self) -> Arc<FileManagementService> {
         Arc::new(FileManagementService::new(
             self.file_write_repository.clone(),
         ))