fix: 用 NSTrackingArea 替代 .onHover 解决标题栏闪烁和红绿灯丢失问题

.onHover 在 macOS 上不可靠，鼠标离开后会误触发 true 导致标题栏短暂回来但没有红绿灯按钮。
改用 NSTrackingArea 的 mouseEntered/mouseExited 做可靠的鼠标追踪。

Sources/MiniPlayerApp.swift

@@ -223,6 +223,54 @@ 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
+    
+    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)
+        }
+        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)
+    }
+}
+
 // MARK: - 可复用的播放器内容视图（主窗口和全屏共用）
 struct PlayerContentView: View {
     @ObservedObject var bridge: PlayerBridge
@@ -327,9 +375,9 @@ struct PlayerContentView: View {
                 }
             }
         }
-        .onHover { hovering in
+        .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) {