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/BookmarkRow.swift

@@ -75,15 +75,16 @@ struct BookmarkRow: View {
 
             if !effectiveTags.isEmpty {
                 ScrollView(.horizontal, showsIndicators: false) {
-                    HStack(spacing: 6) {
-                        ForEach(effectiveTags, id: \.self) { tag in
-                            Text(tag)
-                                .font(.caption.weight(.medium))
-                                .foregroundStyle(.secondary)
-                                .padding(.horizontal, 8)
-                                .padding(.vertical, 3)
-                                .background(Color(.systemGray6))
-                                .clipShape(Capsule())
+                    GlassEffectContainer(spacing: 6) {
+                        HStack(spacing: 6) {
+                            ForEach(effectiveTags, id: \.self) { tag in
+                                Text(tag)
+                                    .font(.caption.weight(.medium))
+                                    .foregroundStyle(.secondary)
+                                    .padding(.horizontal, 8)
+                                    .padding(.vertical, 3)
+                                    .glassEffect(in: Capsule())
+                            }
                         }
                     }
                 }