proper closing of sqlite connection

src/main.rs

@@ -170,6 +170,10 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
         .with_graceful_shutdown(shutdown_signal())
         .await?;
     info!("shutdown complete; closing database");
+    // Explicitly close the pool so SQLite can checkpoint and remove the
+    // WAL/SHM sidecar files. Without this, the pool's background close task
+    // races with process exit and the sidecars can be left behind.
+    db.close().await;
     Ok(())
 }