refactor: optimize item service creation by creating it once per connection

Co-authored-by: aider (openai/andrew/openrouter/qwen/qwen3-coder) <aider@aider.chat>

src/modes/server/common.rs

@@ -15,6 +15,7 @@ use std::sync::Arc;
 use std::time::Instant;
 use tokio::sync::Mutex;
 use utoipa::ToSchema;
+use crate::services::item_service::ItemService;
 
 #[derive(Debug, Clone)]
 pub struct ServerConfig {
@@ -28,6 +29,7 @@ pub struct ServerConfig {
 pub struct AppState {
     pub db: Arc<Mutex<rusqlite::Connection>>,
     pub data_dir: PathBuf,
+    pub item_service: Arc<ItemService>,
 }
 
 #[derive(Serialize, Deserialize, ToSchema)]