Fix tvOS captions list always showing as unavailable in MPV

The captions context menu on tvOS was always empty because it relied on
an .onAppear callback that was never triggered. The captionsPicker view
with .onAppear was only rendered on iOS/macOS, not tvOS.

Changes:
- Access captions directly from player.currentVideo?.captions instead of
  using a state variable populated via .onAppear
- Fix label logic to show "Disabled" when captions are available but not
  selected, and "Not available" only when video has no captions
- Remove unused state variables and helper functions

Shared/Player/Controls/ControlsOverlay.swift

@@ -5,8 +5,6 @@ struct ControlsOverlay: View {
     @ObservedObject private var player = PlayerModel.shared
     private var model = PlayerControlsModel.shared
 
-    @State private var availableCaptions: [Captions] = []
-    @State private var isLoadingCaptions = true
     @State private var contentSize: CGSize = .zero
 
     @Default(.showMPVPlaybackStats) private var showMPVPlaybackStats
@@ -378,11 +376,11 @@ struct ControlsOverlay: View {
                         Text("\(language.description.capitalized) (\(language.rawValue))")
                             .foregroundColor(.accentColor)
                     } else {
-                        if captionsBinding.wrappedValue == nil {
-                            Text("Not available")
-                        } else {
+                        if player.currentVideo?.captions.isEmpty == false {
                             Text("Disabled")
                                 .foregroundColor(.accentColor)
+                        } else {
+                            Text("Not available")
                         }
                     }
                 }
@@ -391,7 +389,7 @@ struct ControlsOverlay: View {
             .contextMenu {
                 Button("Disabled") { captionsBinding.wrappedValue = nil }
 
-                ForEach(availableCaptions) { caption in
+                ForEach(player.currentVideo?.captions ?? []) { caption in
                     Button(caption.description) { captionsBinding.wrappedValue = caption }
                 }
                 Button("Cancel", role: .cancel) {}
@@ -400,7 +398,7 @@ struct ControlsOverlay: View {
     }
 
     @ViewBuilder private var captionsPicker: some View {
-        let captions = availableCaptions
+        let captions = player.currentVideo?.captions ?? []
         Picker("Captions", selection: captionsBinding) {
             if captions.isEmpty {
                 Text("Not available").tag(Captions?.none)
@@ -412,31 +410,6 @@ struct ControlsOverlay: View {
             }
         }
         .disabled(captions.isEmpty)
-        .onAppear {
-            loadCaptions()
-        }
-    }
-
-    private func loadCaptions() {
-        isLoadingCaptions = true
-
-        // Fetch captions asynchronously
-        Task {
-            let fetchedCaptions = await fetchCaptions()
-            await MainActor.run {
-                // Update state on the main thread
-                self.availableCaptions = fetchedCaptions
-                self.isLoadingCaptions = false
-            }
-        }
-    }
-
-    private func fetchCaptions() async -> [Captions] {
-        // Access currentVideo from the main actor context
-        await MainActor.run {
-            // Safely access the main actor-isolated currentVideo property
-            player.currentVideo?.captions ?? []
-        }
     }
 
     private var captionsBinding: Binding<Captions?> {