perf: throttle mouse events and cache window list queries

Performance optimizations from upstream PR jordanbaird#842 patterns:

1. Mouse Event Throttling:
   - Process 1 in 5 mouse moved events (80% reduction)
   - Significantly reduces CPU usage during mouse movement
   - Uses simple counter-based throttling for minimal overhead

2. Window List Caching:
   - Cache menu bar window list for 0.5 seconds
   - Reduces expensive WindowServer IPC calls
   - Hit-testing now uses cached data instead of fresh queries

Combined Impact:
   - Reduced CPU usage during mouse interaction
   - Lower WindowServer communication overhead
   - Smoother app responsiveness
   - Better battery life on laptops

Build: Verified with xcodebuild - BUILD SUCCEEDED

Author: cp09x

Ice/Events/HIDEventManager.swift

@@ -21,6 +21,15 @@ final class HIDEventManager: ObservableObject {
     /// Storage for internal observers.
     private var cancellables = Set<AnyCancellable>()
 
+    /// Counter for throttling mouse moved events.
+    private var mouseMovedCounter = 0
+
+    /// Cached window list for hit-testing.
+    private var cachedWindowList: [CGWindowID] = []
+
+    /// Last time the window list was refreshed.
+    private var lastWindowListRefresh: Date = .distantPast
+
     /// History of the manager's enabled states.
     private var enabledStateStack = [Bool]()
 
@@ -90,7 +99,11 @@ final class HIDEventManager: ObservableObject {
         option: .listenOnly
     ) { [weak self] _, event in
         if let self, isEnabled, let appState, let screen = bestScreen(appState: appState) {
-            handleShowOnHover(appState: appState, screen: screen)
+            mouseMovedCounter += 1
+            if mouseMovedCounter >= 5 {
+                mouseMovedCounter = 0
+                handleShowOnHover(appState: appState, screen: screen)
+            }
         }
         return event
     }
@@ -494,8 +507,12 @@ extension HIDEventManager {
         guard let mouseLocation = MouseHelpers.locationCoreGraphics else {
             return false
         }
-        let windowIDs = Bridging.getMenuBarWindowList(option: [.onScreen, .activeSpace, .itemsOnly])
-        return windowIDs.contains { windowID in
+        let now = Date()
+        if now.timeIntervalSince(lastWindowListRefresh) > 0.5 {
+            cachedWindowList = Bridging.getMenuBarWindowList(option: [.onScreen, .activeSpace, .itemsOnly])
+            lastWindowListRefresh = now
+        }
+        return cachedWindowList.contains { windowID in
             guard let bounds = Bridging.getWindowBounds(for: windowID) else {
                 return false
             }