feat(podcasts): surface mark-played in context menu, full player, and row badge

- Add a long-press context menu on each library row (Play/Pause,
  Mark as Played/Unplayed, Delete).
- Add a Mark as Played/Unplayed control next to Share Episode in the full
  player, tracking the loaded episode across queue advances.
- Show a green checkmark on played rows, on top of the existing Played
  section + dimmed title, so played state reads at a glance.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Marks/Services/PodcastIndex.swift

@@ -54,6 +54,10 @@ enum PodcastIndex {
         all().filter { $0.parentBookmarkUrl == bookmarkUrl || $0.articleUrl == bookmarkUrl }
     }
 
+    static func isPlayed(articleUrl: String) -> Bool {
+        all().first { $0.articleUrl == articleUrl }?.isPlayed ?? false
+    }
+
     /// Mark an episode played (default) or back to unplayed. No-op if unknown.
     static func setPlayed(articleUrl: String, _ played: Bool = true) {
         var entries = all()

Marks/Views/PodcastPlayerView.swift

@@ -358,6 +358,13 @@ struct PodcastPlayerView: View {
     var stopOnDismiss: Bool = false
 
     @Environment(\.dismiss) private var dismiss
+    @State private var isPlayed = false
+
+    /// The episode currently loaded in the player (follows queue advances),
+    /// falling back to the URL this sheet was opened with.
+    private var activeUrl: String {
+        vm.currentArticleUrl.isEmpty ? articleUrl : vm.currentArticleUrl
+    }
 
     var body: some View {
         NavigationStack {
@@ -385,6 +392,10 @@ struct PodcastPlayerView: View {
         }
         .onAppear {
             vm.start(articleUrl: articleUrl, articleTitle: articleTitle, claude: claude)
+            isPlayed = PodcastIndex.isPlayed(articleUrl: activeUrl)
+        }
+        .onChange(of: vm.currentArticleUrl) { _, _ in
+            isPlayed = PodcastIndex.isPlayed(articleUrl: activeUrl)
         }
         .onDisappear {
             if stopOnDismiss { vm.stop() }
@@ -495,6 +506,19 @@ struct PodcastPlayerView: View {
                     .glassEffect(in: Capsule())
             }
 
+            HStack(spacing: 28) {
+                Button {
+                    isPlayed.toggle()
+                    PodcastIndex.setPlayed(articleUrl: activeUrl, isPlayed)
+                } label: {
+                    Label(isPlayed ? "Mark as Unplayed" : "Mark as Played",
+                          systemImage: isPlayed ? "checkmark.circle.fill" : "checkmark.circle")
+                        .font(.system(size: 14, weight: .medium))
+                        .foregroundStyle(isPlayed ? Color.green : .secondary)
+                }
+                .buttonStyle(.plain)
+                .contentTransition(.symbolEffect(.replace))
+
                 if let url = URL(string: articleUrl) {
                     ShareLink(item: url, subject: Text(vm.currentArticleTitle.isEmpty ? "Marks Podcast" : vm.currentArticleTitle)) {
                         Label("Share Episode", systemImage: "square.and.arrow.up")
@@ -504,6 +528,7 @@ struct PodcastPlayerView: View {
                 }
             }
         }
+    }
 
     private func failedView(message: String) -> some View {
         VStack(spacing: 16) {
@@ -713,6 +738,12 @@ struct PodcastLibraryView: View {
                     .foregroundStyle(.secondary)
             }
             Spacer()
+            if entry.isPlayed {
+                Image(systemName: "checkmark.circle.fill")
+                    .font(.system(size: 15))
+                    .foregroundStyle(.green)
+                    .accessibilityLabel("Played")
+            }
             Button {
                 play(entry)
             } label: {
@@ -743,6 +774,29 @@ struct PodcastLibraryView: View {
                 Label("Delete", systemImage: "trash")
             }
         }
+        .contextMenu {
+            Button {
+                play(entry)
+            } label: {
+                Label(isCurrent(entry) && vm.isPlaying ? "Pause" : "Play",
+                      systemImage: isCurrent(entry) && vm.isPlaying ? "pause" : "play")
+            }
+            Button {
+                setPlayed(entry, !entry.isPlayed)
+            } label: {
+                if entry.isPlayed {
+                    Label("Mark as Unplayed", systemImage: "circle")
+                } else {
+                    Label("Mark as Played", systemImage: "checkmark.circle")
+                }
+            }
+            Divider()
+            Button(role: .destructive) {
+                deleteEntry(entry)
+            } label: {
+                Label("Delete", systemImage: "trash")
+            }
+        }
     }
 
     private func setPlayed(_ entry: PodcastEntry, _ played: Bool) {