Add an option to share videos via privacy frontend URLs

When enabled (the default), share links to YouTube videos point to the
active source's web watch page instead of youtube.com. Invidious serves
its frontend at the API URL; Piped uses its configured frontend URL.
Videos the active source can't serve (PeerTube, extracted sources) and
sources without a web frontend keep their original links.

The toggle lives in Settings > Layout & Navigation > Sharing on iOS and
macOS, and is shown only when an enabled source has a web watch page.

Yattee/Views/Components/PlayerPillButtonView.swift

@@ -10,6 +10,8 @@
 import SwiftUI
 
 struct PlayerPillButtonView: View {
+    @Environment(\.appEnvironment) private var appEnvironment
+
     let configuration: ControlButtonConfiguration
     let isPlaying: Bool
     let hasNext: Bool
@@ -199,7 +201,7 @@ struct PlayerPillButtonView: View {
     private var shareButton: some View {
         Group {
             if let video {
-                ShareLink(item: video.shareURL) {
+                ShareLink(item: appEnvironment?.shareURL(for: video) ?? video.shareURL) {
                     genericButtonLabel
                 }
                 .buttonStyle(.plain)

Yattee/Views/Components/VideoContextMenu.swift

@@ -280,7 +280,7 @@ struct VideoContextMenuContent: View {
 
         // Share
         #if !os(tvOS)
-        ShareLink(item: video.shareURL) {
+        ShareLink(item: appEnvironment?.shareURL(for: video) ?? video.shareURL) {
             Label(String(localized: "video.context.share"), systemImage: "square.and.arrow.up")
         }
         #endif

Yattee/Views/Components/VideoSwipeActionsModifier.swift

@@ -191,7 +191,7 @@ struct VideoSwipeActionsModifier: ViewModifier {
     private func shareVideo() {
         #if os(iOS)
         let activityVC = UIActivityViewController(
-            activityItems: [video.shareURL],
+            activityItems: [appEnvironment?.shareURL(for: video) ?? video.shareURL],
             applicationActivities: nil
         )
         if let windowScene = UIApplication.shared.connectedScenes.first as? UIWindowScene,
@@ -217,7 +217,7 @@ struct VideoSwipeActionsModifier: ViewModifier {
         #elseif os(macOS)
         let pasteboard = NSPasteboard.general
         pasteboard.clearContents()
-        pasteboard.setString(video.shareURL.absoluteString, forType: .string)
+        pasteboard.setString((appEnvironment?.shareURL(for: video) ?? video.shareURL).absoluteString, forType: .string)
         #endif
     }
 

Yattee/Views/Player/ControlsSectionRenderer.swift

@@ -11,6 +11,8 @@ import SwiftUI
 
 /// Renders a horizontal row of control buttons based on layout configuration.
 struct ControlsSectionRenderer: View {
+    @Environment(\.appEnvironment) private var appEnvironment
+
     let section: LayoutSection
     let actions: PlayerControlsActions
     let globalSettings: GlobalLayoutSettings
@@ -925,7 +927,7 @@ struct ControlsSectionRenderer: View {
     @ViewBuilder
     private var shareButton: some View {
         if let video = actions.currentVideo {
-            ShareLink(item: video.shareURL) {
+            ShareLink(item: appEnvironment?.shareURL(for: video) ?? video.shareURL) {
                 buttonContent(systemImage: "square.and.arrow.up", tint: .white)
             }
         }

Yattee/Views/Player/MiniPlayerView.swift

@@ -572,7 +572,7 @@ struct MiniPlayerView: View {
     @ViewBuilder
     private func shareButton(config: ControlButtonConfiguration) -> some View {
         if let video = currentVideo {
-            ShareLink(item: video.shareURL) {
+            ShareLink(item: appEnvironment?.shareURL(for: video) ?? video.shareURL) {
                 Image(systemName: "square.and.arrow.up")
                     .font(isTabAccessory ? .title3 : .title2)
                     .frame(width: 32, height: 32)

Yattee/Views/Player/macOS/MacOSControlsSectionRenderer.swift

@@ -670,7 +670,7 @@ struct MacOSControlsSectionRenderer: View {
     @ViewBuilder
     private var shareButton: some View {
         if let video = actions.currentVideo {
-            ShareLink(item: video.shareURL) {
+            ShareLink(item: appEnvironment?.shareURL(for: video) ?? video.shareURL) {
                 buttonLabel(systemImage: "square.and.arrow.up")
             }
             .buttonStyle(buttonStyleForContext)

Yattee/Views/Settings/LayoutNavigationSettingsView.swift

@@ -22,6 +22,7 @@ struct LayoutNavigationSettingsView: View {
                 #else
                 VideoActionsSection(settings: settings)
                 LinkActionSection(settings: settings)
+                SharingSection(settings: settings)
                 ClipboardSection(settings: settings)
                 #endif
                 #if os(iOS)
@@ -143,6 +144,32 @@ private struct LinkActionSection: View {
     }
 }
 
+// MARK: - Sharing Section
+
+#if !os(tvOS)
+private struct SharingSection: View {
+    @Environment(\.appEnvironment) private var appEnvironment
+    @Bindable var settings: SettingsManager
+
+    /// Shown only when a source with a web watch page exists — without one
+    /// the toggle can't change anything.
+    private var hasPrivacyFrontendSource: Bool {
+        appEnvironment?.instancesManager.enabledInstances.contains { $0.watchPageBaseURL != nil } ?? false
+    }
+
+    var body: some View {
+        if hasPrivacyFrontendSource {
+            SettingsFormSection("settings.behavior.sharing.header", footer: "settings.behavior.privacyFrontendSharing.footer") {
+                Toggle(
+                    String(localized: "settings.behavior.privacyFrontendSharing"),
+                    isOn: $settings.privacyFrontendSharingEnabled
+                )
+            }
+        }
+    }
+}
+#endif
+
 // MARK: - Clipboard Section
 
 private struct ClipboardSection: View {

Yattee/Views/Video/VideoInfoView.swift

@@ -1173,7 +1173,7 @@ struct VideoInfoView: View {
 
                 // Share button
                 if let video = displayedVideo {
-                    ShareLink(item: video.shareURL) {
+                    ShareLink(item: appEnvironment?.shareURL(for: video) ?? video.shareURL) {
                         #if os(macOS)
                         Label(String(localized: "video.share"), systemImage: "square.and.arrow.up")
                             .font(.body)