style(ui): adopt Liquid Glass on opaque controls

Swap hardcoded systemGray/Color.blue pill and button fills for the iOS 26
Liquid Glass APIs so controls read native under the new design system:
- BookmarkRow tag chips: glassEffect in a GlassEffectContainer
- Podcast speed button: glassEffect capsule
- Podcast retry + Onboarding Connect: glassProminent button style

Onboarding text-field fills left as systemGray6 (standard adaptive field
fill; glass behind editable text hurts legibility).

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

Marks/Views/PodcastPlayerView.swift

@@ -464,8 +464,7 @@ struct PodcastPlayerView: View {
                     .foregroundStyle(.secondary)
                     .padding(.horizontal, 14)
                     .padding(.vertical, 7)
-                    .background(Color(.systemGray5))
-                    .clipShape(Capsule())
+                    .glassEffect(in: Capsule())
             }
 
             if let url = URL(string: articleUrl) {
@@ -494,12 +493,10 @@ struct PodcastPlayerView: View {
             } label: {
                 Label("Retry", systemImage: "arrow.clockwise")
                     .font(.system(size: 15, weight: .semibold))
-                    .foregroundStyle(.white)
-                    .padding(.horizontal, 24)
-                    .padding(.vertical, 10)
-                    .background(Color.blue)
-                    .clipShape(Capsule())
             }
+            .buttonStyle(.glassProminent)
+            .tint(.blue)
+            .buttonBorderShape(.capsule)
             .padding(.top, 4)
         }
     }