feat(media): auto-detect Pear Desktop for seamless YouTube Music sync

When Pear Desktop (com.github.th-ch.youtube-music) is running,
MusicManager now automatically switches to YouTubeMusicController
for seamless media sync without requiring manual settings changes.

Changes:
- Added NSWorkspace notification observers for app launch/terminate
- Auto-switches to YouTubeMusicController when Pear Desktop launches
- Reverts to user's preferred controller when Pear Desktop terminates
- Checks for Pear Desktop at startup
- Respects manual settings changes (won't override user preference)

DynamicIsland/managers/MusicManager.swift

@@ -71,6 +71,10 @@ class MusicManager: ObservableObject {
     // Active controller
     private var activeController: (any MediaControllerProtocol)?
 
+    // Pear Desktop auto-detection
+    private static let pearDesktopBundleID = YouTubeMusicConfiguration.default.bundleIdentifier
+    private var isPearDesktopAutoSwitched: Bool = false
+
     // Published properties for UI
     @Published var songTitle: String = "I'm Handsome"
     @Published var artistName: String = "Me"
@@ -126,10 +130,14 @@ class MusicManager: ObservableObject {
         // Listen for changes to the default controller preference
         NotificationCenter.default.publisher(for: Notification.Name.mediaControllerChanged)
             .sink { [weak self] _ in
+                self?.isPearDesktopAutoSwitched = false
                 self?.setActiveControllerBasedOnPreference()
             }
             .store(in: &cancellables)
 
+        // Observe Pear Desktop launch/terminate for auto-detection
+        setupPearDesktopAutoDetection()
+
         // Initialize deprecation check asynchronously
         Task { @MainActor in
             do {
@@ -140,11 +148,55 @@ class MusicManager: ObservableObject {
                 self.isNowPlayingDeprecated = false
             }
             
-            // Initialize the active controller after deprecation check
+            // Check if Pear Desktop is already running at startup
-            self.setActiveControllerBasedOnPreference()
+            let pearDesktopRunning = NSWorkspace.shared.runningApplications.contains {
+                $0.bundleIdentifier == Self.pearDesktopBundleID
+            }
+            
+            if pearDesktopRunning {
+                print("[MusicManager] Pear Desktop detected at startup, auto-switching to YouTubeMusicController")
+                self.isPearDesktopAutoSwitched = true
+                if let controller = self.createController(for: .youtubeMusic) {
+                    self.setActiveController(controller)
+                }
+            } else {
+                // Initialize the active controller after deprecation check
+                self.setActiveControllerBasedOnPreference()
+            }
         }
     }
 
+    // MARK: - Pear Desktop Auto-Detection
+    private func setupPearDesktopAutoDetection() {
+        NSWorkspace.shared.notificationCenter.publisher(for: NSWorkspace.didLaunchApplicationNotification)
+            .sink { [weak self] notification in
+                guard let self = self,
+                      let app = notification.userInfo?[NSWorkspace.applicationUserInfoKey] as? NSRunningApplication,
+                      app.bundleIdentifier == Self.pearDesktopBundleID else { return }
+
+                print("[MusicManager] Pear Desktop launched, auto-switching to YouTubeMusicController")
+                self.isPearDesktopAutoSwitched = true
+                if let controller = self.createController(for: .youtubeMusic) {
+                    self.setActiveController(controller)
+                }
+            }
+            .store(in: &cancellables)
+
+        NSWorkspace.shared.notificationCenter.publisher(for: NSWorkspace.didTerminateApplicationNotification)
+            .sink { [weak self] notification in
+                guard let self = self,
+                      let app = notification.userInfo?[NSWorkspace.applicationUserInfoKey] as? NSRunningApplication,
+                      app.bundleIdentifier == Self.pearDesktopBundleID else { return }
+
+                print("[MusicManager] Pear Desktop terminated, reverting to preferred controller")
+                if self.isPearDesktopAutoSwitched {
+                    self.isPearDesktopAutoSwitched = false
+                    self.setActiveControllerBasedOnPreference()
+                }
+            }
+            .store(in: &cancellables)
+    }
+
     deinit {
         destroy()
     }