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/interfaces/api/handlers/trash_handler.rs

@@ -4,7 +4,7 @@ use axum::http::StatusCode;
 use serde_json::json;
 use tracing::{debug, error, instrument, warn};
 
-// use crate::application::ports::trash_ports::TrashUseCase;
+use crate::application::ports::trash_ports::TrashUseCase;
 use crate::common::di::AppState;
 use crate::interfaces::middleware::auth::{AuthUser, OptionalAuthUser};
 use std::sync::Arc;