Rename YouTube Enhancements settings to Integrations

Also swap the icon to puzzlepiece.extension, which better conveys that
this section houses third-party service hookups (SponsorBlock, Return
YouTube Dislike, DeArrow, short-link resolution) rather than being
YouTube-specific.

Hide the Resolve Short Links toggle on tvOS — there's no way to tap
inline description links or reach a system browser there — and tighten
the openInSystemBrowser platform guards so the iOS-only UIApplication
path isn't compiled on tvOS.

Yattee/Views/Components/ResolvedLinkPromptsModifier.swift

@@ -96,9 +96,9 @@ struct ResolvedLinkPromptsModifier: ViewModifier {
 
     @MainActor
     private func openInSystemBrowser(_ url: URL) {
-        #if canImport(UIKit) && !os(watchOS)
+        #if os(iOS)
         UIApplication.shared.open(url)
-        #elseif canImport(AppKit)
+        #elseif os(macOS)
         NSWorkspace.shared.open(url)
         #endif
     }