feat(podcasts): add a Podcasts tab to list and play on demand

Surface every podcast in PodcastIndex as a top-level tab instead of a
buried sheet. Repurpose PodcastLibraryView into the tab: play/pause toggle
per episode, a now-playing bar that opens the full player, swipe/Edit to
delete. Uses the shared podcastPlayer so playback state is consistent
across tabs. Removes the redundant Podcasts entry from the bookmarks menu.

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

Marks/Views/PodcastPlayerView.swift

@@ -597,12 +597,15 @@ struct MiniPlayerView: View {
 
 // MARK: - Podcast library
 
+/// The Podcasts tab: lists every podcast generated in the app (from
+/// `PodcastIndex`) and plays them on demand through the shared player, with a
+/// now-playing bar that opens the full player.
 struct PodcastLibraryView: View {
     let vm: PodcastPlayerViewModel
     let claude: ClaudeService
 
     @State private var entries: [PodcastEntry] = []
-    @Environment(\.dismiss) private var dismiss
+    @State private var showFullPlayer = false
 
     var body: some View {
         NavigationStack {
@@ -611,7 +614,7 @@ struct PodcastLibraryView: View {
                     ContentUnavailableView(
                         "No Podcasts",
                         systemImage: "headphones",
-                        description: Text("Podcasts you generate will appear here.")
+                        description: Text("Podcasts you generate from bookmarks will appear here.")
                     )
                 } else {
                     List {
@@ -627,14 +630,12 @@ struct PodcastLibraryView: View {
                                 }
                                 Spacer()
                                 Button {
-                                    vm.start(articleUrl: entry.articleUrl,
-                                             articleTitle: entry.title ?? "",
-                                             claude: claude)
-                                    dismiss()
+                                    play(entry)
                                 } label: {
-                                    Image(systemName: "play.circle.fill")
+                                    Image(systemName: isCurrent(entry) && vm.isPlaying ? "pause.circle.fill" : "play.circle.fill")
                                         .font(.system(size: 36))
                                         .foregroundStyle(.blue)
+                                        .contentTransition(.symbolEffect(.replace))
                                 }
                                 .buttonStyle(.plain)
                             }
@@ -655,16 +656,45 @@ struct PodcastLibraryView: View {
                 }
             }
             .navigationTitle("Podcasts")
-            .navigationBarTitleDisplayMode(.inline)
             .toolbar {
-                ToolbarItem(placement: .topBarTrailing) {
-                    Button("Done") { dismiss() }
+                if !entries.isEmpty {
+                    ToolbarItem(placement: .topBarTrailing) { EditButton() }
                 }
             }
+            .overlay(alignment: .bottom) {
+                if !vm.currentArticleUrl.isEmpty {
+                    MiniPlayerView(vm: vm) { showFullPlayer = true }
+                        .padding(.horizontal)
+                        .padding(.bottom, 8)
+                        .transition(.move(edge: .bottom).combined(with: .opacity))
+                }
+            }
+            .animation(.spring(duration: 0.3), value: vm.currentArticleUrl.isEmpty)
+            .sheet(isPresented: $showFullPlayer) {
+                PodcastPlayerView(
+                    vm: vm,
+                    articleUrl: vm.currentArticleUrl,
+                    articleTitle: vm.currentArticleTitle,
+                    claude: claude,
+                    stopOnDismiss: false
+                )
+            }
         }
         .onAppear { entries = PodcastIndex.all() }
     }
 
+    private func isCurrent(_ entry: PodcastEntry) -> Bool {
+        vm.currentArticleUrl == entry.articleUrl
+    }
+
+    private func play(_ entry: PodcastEntry) {
+        if isCurrent(entry) {
+            vm.togglePlayPause()
+        } else {
+            vm.start(articleUrl: entry.articleUrl, articleTitle: entry.title ?? "", claude: claude)
+        }
+    }
+
     private func deleteEntry(_ entry: PodcastEntry) {
         PodcastIndex.remove(articleUrl: entry.articleUrl)
         entries.removeAll { $0.articleUrl == entry.articleUrl }