perf(server): offload sync disk/db IO to tokio blocking thread pool

Makes apply_sync_write, write_to_local_delta, and store modify truly async, preventing the mcp-memory-server from locking the tokio executor during disk IO

server/src/main.rs

@@ -91,8 +91,11 @@ async fn reconcile_worker(state: Arc<MemoryState>) {
         };
         let has_files = glob::glob(&pattern).map(|p| p.count() > 0).unwrap_or(false);
         if has_local || has_files {
-            state.apply_sync_write(|_master| {});
-            state.rebuild_index();
+            state.apply_sync_write(|_master| {}).await;
+            let state_clone = state.clone();
+            let _ = tokio::task::spawn_blocking(move || {
+                state_clone.rebuild_index();
+            }).await;
         }
 
         let now = SystemTime::now()