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/ports/zip_ports.rs

@@ -5,14 +5,12 @@
 //! implementation details.
 
 use crate::common::errors::DomainError;
-use async_trait::async_trait;
 use tempfile::NamedTempFile;
 
 /// Port for ZIP archive operations.
 ///
 /// Implementations handle the actual ZIP file creation, compression,
 /// and recursive folder traversal.
-#[async_trait]
 pub trait ZipPort: Send + Sync + 'static {
     /// Create a ZIP archive containing the contents of a folder (recursively).
     ///