feat: adopt a two-pane start screen

Sources/App/PlaybackProgress.swift

@@ -1,6 +1,12 @@
 import Foundation
 
 struct PlaybackProgress {
+    struct RecentMedia: Equatable, Identifiable {
+        let url: URL
+        let title: String
+        var id: URL { url }
+    }
+
     private let defaults: UserDefaults
 
     init(defaults: UserDefaults = .standard) {
@@ -28,6 +34,22 @@ struct PlaybackProgress {
         defaults.set(position, forKey: key)
     }
 
+    var recentMedia: [RecentMedia] {
+        (defaults.array(forKey: "recentMedia") as? [[String: String]] ?? []).compactMap {
+            guard let text = $0["url"], let url = URL(string: text), let title = $0["title"] else { return nil }
+            return RecentMedia(url: url, title: title)
+        }
+    }
+
+    func recordRecent(_ url: URL, title: String) {
+        let url = url.isFileURL ? url.standardizedFileURL.resolvingSymlinksInPath() : url
+        var entries = recentMedia
+        entries.removeAll { $0.url == url }
+        entries.insert(RecentMedia(url: url, title: title), at: 0)
+        defaults.set(entries.prefix(6).map { ["url": $0.url.absoluteString, "title": $0.title] },
+                     forKey: "recentMedia")
+    }
+
     private func key(for url: URL) -> String {
         // YouTube callers supply the canonical webpage URL, never an expiring media URL.
         return "playbackPosition:" + (url.isFileURL ? url.standardizedFileURL.resolvingSymlinksInPath().absoluteString : url.absoluteString)