chore: conditionally import AtomicU64 only on non-macOS

AtomicU64 is only used in #[cfg(not(target_os = macos))] blocks
(focus-loss debounce for Windows/Linux). On macOS it generates an
unused import warning. Moved the import behind the same cfg guard.

Author: VariableThe

src-tauri/src/lib.rs

@@ -10,7 +10,9 @@ mod tray;
 
 use commands::shortcuts::GlobalShortcutState;
 use commands::notifications::NotificationState;
-use std::sync::atomic::{AtomicBool, AtomicU64, Ordering};
+#[cfg(not(target_os = "macos"))]
+use std::sync::atomic::AtomicU64;
+use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Arc;
 use tauri_plugin_window_state::{StateFlags, WindowExt};