fix: 用 NSEvent.addLocalMonitorForEvents 替代 .onHover/tracking area

之前的方案（.onHover 和 .background tracking area）都不可靠：
- .onHover 在 macOS 上行为不稳定
- .background() 里的 NSView 被 AVPlayerLayer 挡住收不到鼠标事件

新方案：用 NSEvent.addLocalMonitorForEvents 在应用层监听 mouseMoved 事件，
直接检测鼠标是否在窗口 frame 内，完全绕过 SwiftUI 的 hover 机制。
加上双层防抖（lastState + currentlyVisible 检查）避免重复设置。

Sources/MiniPlayerApp.swift

@@ -223,51 +223,35 @@ class PlayerLayerHostView: NSView {
     }
 }
 
-// MARK: - 可靠的鼠标追踪（替代 SwiftUI .onHover 的不可靠行为）
-struct MouseTrackingArea: NSViewRepresentable {
-    let onHoverChange: @MainActor (Bool) -> Void
+// MARK: - 窗口级鼠标监控（替代 .onHover 和 background tracking area）
+class WindowMouseMonitor {
+    static let shared = WindowMouseMonitor()
+    private var monitor: Any?
+    private var lastState: Bool?
     
-    func makeNSView(context: Context) -> MouseTrackingNSView {
-        let view = MouseTrackingNSView()
-        view.onHoverChange = onHoverChange
-        return view
-    }
-    
-    func updateNSView(_ nsView: MouseTrackingNSView, context: Context) {
-        nsView.onHoverChange = onHoverChange
-    }
-}
-
-class MouseTrackingNSView: NSView {
-    var onHoverChange: (@MainActor (Bool) -> Void)?
-    private var trackingArea: NSTrackingArea?
-    private var isHovering = false
-    
-    override func updateTrackingAreas() {
-        super.updateTrackingAreas()
-        if let existing = trackingArea {
-            removeTrackingArea(existing)
+    func startMonitoring() {
+        guard monitor == nil else { return }
+        monitor = NSEvent.addLocalMonitorForEvents(matching: [.mouseMoved]) { [weak self] event in
+            self?.handleMouseMoved(event)
+            return event
         }
-        let area = NSTrackingArea(
-            rect: .zero,
-            options: [.mouseEnteredAndExited, .activeInKeyWindow, .inVisibleRect],
-            owner: self,
-            userInfo: nil
-        )
-        addTrackingArea(area)
-        trackingArea = area
     }
     
-    override func mouseEntered(with event: NSEvent) {
-        guard !isHovering else { return }
-        isHovering = true
-        onHoverChange?(true)
-    }
-    
-    override func mouseExited(with event: NSEvent) {
-        guard isHovering else { return }
-        isHovering = false
-        onHoverChange?(false)
+    private func handleMouseMoved(_ event: NSEvent) {
+        guard let win = NSApplication.shared.windows.first(where: { $0.isVisible && !($0 is NSPanel) }) else { return }
+        let mouseScreenPos = NSEvent.mouseLocation
+        let isInside = win.frame.contains(mouseScreenPos)
+        guard isInside != lastState else { return }
+        lastState = isInside
+        NSLog("[MiniPlayer] WindowMouseMonitor: mouseInside=%d", isInside)
+        // 防抖：状态没变就不动
+        let currentlyVisible = win.titleVisibility == .visible
+        guard currentlyVisible != isInside else { return }
+        win.titlebarAppearsTransparent = !isInside
+        win.titleVisibility = isInside ? .visible : .hidden
+        win.standardWindowButton(.closeButton)?.isHidden = !isInside
+        win.standardWindowButton(.miniaturizeButton)?.isHidden = !isInside
+        win.standardWindowButton(.zoomButton)?.isHidden = !isInside
     }
 }
 
@@ -289,15 +273,6 @@ struct PlayerContentView: View {
         }
     }
     
-    private func setWindowTitleBarVisible(_ visible: Bool) {
-        guard let win = NSApplication.shared.windows.first(where: { $0.isVisible }) else { return }
-        win.titlebarAppearsTransparent = !visible
-        win.titleVisibility = visible ? .visible : .hidden
-        win.standardWindowButton(.closeButton)?.isHidden = !visible
-        win.standardWindowButton(.miniaturizeButton)?.isHidden = !visible
-        win.standardWindowButton(.zoomButton)?.isHidden = !visible
-    }
-    
     var body: some View {
         ZStack(alignment: .topLeading) {
             Color.black.ignoresSafeArea()
@@ -375,9 +350,6 @@ struct PlayerContentView: View {
                 }
             }
         }
-        .background(MouseTrackingArea(onHoverChange: { hovering in
-            setWindowTitleBarVisible(hovering)
-        }))
         .onAppear {
             // 初始状态：标题栏完全隐藏（含红绿灯按钮）
             DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) {
@@ -388,6 +360,12 @@ struct PlayerContentView: View {
                 win.standardWindowButton(.closeButton)?.isHidden = true
                 win.standardWindowButton(.miniaturizeButton)?.isHidden = true
                 win.standardWindowButton(.zoomButton)?.isHidden = true
+                
+                // 启用 mouseMoved 事件（默认不发送）
+                win.acceptsMouseMovedEvents = true
+                
+                // 用全局鼠标事件监听器替代 .onHover
+                WindowMouseMonitor.shared.startMonitoring()
             }
         }
         .onChange(of: showToolbar) { _, newValue in