fix(perf): replace std::sync::Mutex with moka lock-free cache in async context

Eliminates deadlock risk under concurrent load:
- SearchService: Arc<Mutex<HashMap>> → moka::sync::Cache with automatic TTL + LRU
  - Removed manual cleanup task, TTL checking, eviction logic (~90 lines)
  - get_from_cache/store_in_cache are now single lock-free calls
  - clear_search_cache uses invalidate_all()
- HttpCache: Arc<Mutex<HashMap>> → moka::sync::Cache
  - Removed stats(), cleanup(), evict_oldest() manual methods
  - Removed CacheEntry.timestamp/max_age fields (moka handles internally)
  - Removed start_cache_cleanup_task (moka evicts lazily)
- routes.rs: Removed dead HttpCache instantiation and unused TTL variables

Impact: std::sync::Mutex::lock() blocked Tokio worker threads; N concurrent
requests (N = CPU count) could freeze the entire server. moka::sync::Cache
is lock-free and designed for async runtimes — zero contention.

src/interfaces/api/routes.rs

@@ -17,8 +17,6 @@ async fn get_version() -> AxumJson<serde_json::Value> {
     }))
 }
 
-use crate::interfaces::middleware::cache::{HttpCache, start_cache_cleanup_task};
-
 use crate::application::services::batch_operations::BatchOperationService;
 
 use crate::interfaces::api::handlers::admin_handler;
@@ -110,17 +108,6 @@ pub fn create_api_routes(app_state: &AppState) -> Router<AppState> {
         batch_service: batch_service.clone(),
     };
 
-    // Implement HTTP Cache
-    let http_cache = HttpCache::new();
-
-    // Define TTL values for different resource types (in seconds)
-    let _folders_ttl = 300; // 5 minutes
-    let _files_list_ttl = 300; // 5 minutes
-    let _i18n_ttl = 3600; // 1 hour
-
-    // Start the cleanup task for HTTP cache
-    start_cache_cleanup_task(http_cache.clone());
-
     // Create the basic folders router with service operations
     let folders_basic_router = Router::new()
         .route("/", post(FolderHandler::create_folder))