Add details panel preset settings UI and default visibility

Phase 2 of the player panels redesign:

- New "Details Panel" screen in Player Controls settings: page
  reorder/enable list with per-page editor (info element toggles),
  and a default panel visibility picker (hidden/visible/remember).
- PlayerControlsSettingsViewModel gains panelSettings bindings with
  the usual debounced-save flow; the last enabled page cannot be
  disabled.
- Built-in presets bumped to v9 with explicit default panelSettings.
- The preset's default visibility now drives the wide-layout panel
  on player open and on entering landscape, replacing the hard
  hidden resets; "remember" restores the new detailsPanelLastVisible
  setting recorded on user toggles. Applied once per expanded player
  session (flag on NavigationCoordinator survives re-mounts).
- WideScreenPlayerLayout picks up external visibility writes so the
  async-loaded default reaches the mounted layout.
- Unit tests for PanelSettings Codable compatibility (round-trip,
  old JSON, unknown page types/discriminators/enum values); removed
  stale PlayerInfoTab tests left from Phase 1.

Yattee/Views/Settings/PlayerControls/PanelPageEditorView.swift

@@ -0,0 +1,127 @@
+//
+//  PanelPageEditorView.swift
+//  Yattee
+//
+//  Settings editor for a single details panel page.
+//
+
+import SwiftUI
+
+#if os(iOS) || os(macOS)
+
+struct PanelPageEditorView: View {
+    let pageType: PanelPageType
+    @Bindable var viewModel: PlayerControlsSettingsViewModel
+
+    // Local state for immediate UI updates
+    @State private var isEnabled: Bool = true
+    @State private var showDescription: Bool = true
+    @State private var showStatsRow: Bool = true
+    @State private var showChannelRow: Bool = true
+
+    private var configuration: PanelPageConfiguration? {
+        viewModel.panelSettings.configuration(for: pageType)
+    }
+
+    /// Whether this is the only enabled page; the last one cannot be disabled.
+    private var isLastEnabledPage: Bool {
+        isEnabled && viewModel.enabledPanelPageCount <= 1
+    }
+
+    var body: some View {
+        Form {
+            enabledSection
+
+            if pageType == .info {
+                infoElementsSection
+            }
+        }
+        .navigationTitle(pageType.displayName)
+        #if os(iOS)
+        .navigationBarTitleDisplayMode(.inline)
+        #elseif os(macOS)
+        .formStyle(.grouped)
+        #endif
+        .opaqueSettingsFormBackground()
+        .onAppear {
+            syncLocalState()
+        }
+        .onChange(of: viewModel.activePreset?.id) { _, _ in
+            syncLocalState()
+        }
+    }
+
+    // MARK: - Enabled Section
+
+    private var enabledSection: some View {
+        Section {
+            Toggle(
+                String(localized: "panel.settings.page.enabled"),
+                isOn: $isEnabled
+            )
+            .disabled(!viewModel.canEditActivePreset || isLastEnabledPage)
+            .onChange(of: isEnabled) { _, newValue in
+                guard newValue != configuration?.isEnabled else { return }
+                viewModel.setPanelPageEnabled(pageType, isEnabled: newValue)
+            }
+        } footer: {
+            if isLastEnabledPage {
+                Text(String(localized: "panel.settings.page.lastEnabled.footer"))
+            } else if !viewModel.canEditActivePreset {
+                Text(String(localized: "settings.playerControls.duplicateToEdit"))
+            }
+        }
+    }
+
+    // MARK: - Info Elements Section
+
+    private var infoElementsSection: some View {
+        Section {
+            Toggle(
+                String(localized: "panel.settings.info.showStatsRow"),
+                isOn: $showStatsRow
+            )
+            .onChange(of: showStatsRow) { _, newValue in
+                guard newValue != infoSettings.effectiveShowStatsRow else { return }
+                viewModel.updatePanelInfoSettingsSync { $0.showStatsRow = newValue }
+            }
+
+            Toggle(
+                String(localized: "panel.settings.info.showChannelRow"),
+                isOn: $showChannelRow
+            )
+            .onChange(of: showChannelRow) { _, newValue in
+                guard newValue != infoSettings.effectiveShowChannelRow else { return }
+                viewModel.updatePanelInfoSettingsSync { $0.showChannelRow = newValue }
+            }
+
+            Toggle(
+                String(localized: "panel.settings.info.showDescription"),
+                isOn: $showDescription
+            )
+            .onChange(of: showDescription) { _, newValue in
+                guard newValue != infoSettings.effectiveShowDescription else { return }
+                viewModel.updatePanelInfoSettingsSync { $0.showDescription = newValue }
+            }
+        } header: {
+            Text(String(localized: "panel.settings.elements.header"))
+        }
+        .disabled(!viewModel.canEditActivePreset)
+    }
+
+    // MARK: - Helpers
+
+    private var infoSettings: InfoPageSettings {
+        configuration?.infoSettings ?? InfoPageSettings()
+    }
+
+    private func syncLocalState() {
+        isEnabled = configuration?.isEnabled ?? true
+        let info = infoSettings
+        showDescription = info.effectiveShowDescription
+        showStatsRow = info.effectiveShowStatsRow
+        showChannelRow = info.effectiveShowChannelRow
+    }
+}
+
+#endif

Yattee/Views/Settings/PlayerControls/PanelSettingsView.swift

@@ -0,0 +1,110 @@
+//
+//  PanelSettingsView.swift
+//  Yattee
+//
+//  Settings editor for the player details panel pages.
+//
+
+import SwiftUI
+
+#if os(iOS) || os(macOS)
+
+struct PanelSettingsView: View {
+    @Bindable var viewModel: PlayerControlsSettingsViewModel
+
+    // Local state for immediate UI updates
+    @State private var defaultVisibility: PanelDefaultVisibility = .hidden
+
+    var body: some View {
+        List {
+            visibilitySection
+            pagesSection
+        }
+        .navigationTitle(String(localized: "settings.playerControls.detailsPanel"))
+        #if os(iOS)
+        .navigationBarTitleDisplayMode(.inline)
+        #elseif os(macOS)
+        .formStyle(.grouped)
+        #endif
+        .opaqueSettingsFormBackground()
+        .toolbar {
+            #if os(iOS)
+            EditButton()
+            #endif
+        }
+        .onAppear {
+            syncLocalState()
+        }
+        .onChange(of: viewModel.activePreset?.id) { _, _ in
+            syncLocalState()
+        }
+    }
+
+    // MARK: - Visibility Section
+
+    private var visibilitySection: some View {
+        Section {
+            Picker(
+                String(localized: "panel.settings.defaultVisibility"),
+                selection: $defaultVisibility
+            ) {
+                ForEach(PanelDefaultVisibility.allCases, id: \.self) { visibility in
+                    Text(visibility.displayName).tag(visibility)
+                }
+            }
+            .disabled(!viewModel.canEditActivePreset)
+            .onChange(of: defaultVisibility) { _, newValue in
+                guard newValue != viewModel.panelDefaultVisibility else { return }
+                viewModel.syncPanelDefaultVisibility(newValue)
+            }
+        } footer: {
+            Text(String(localized: "panel.settings.defaultVisibility.footer"))
+        }
+    }
+
+    // MARK: - Pages Section
+
+    private var pagesSection: some View {
+        Section {
+            ForEach(viewModel.panelPages) { page in
+                pageRow(for: page)
+            }
+            .onMove { source, destination in
+                viewModel.movePanelPages(fromOffsets: source, toOffset: destination)
+            }
+        } header: {
+            Text(String(localized: "panel.settings.pages.header"))
+        } footer: {
+            if viewModel.canEditActivePreset {
+                Text(String(localized: "panel.settings.pages.footer"))
+            } else {
+                Text(String(localized: "settings.playerControls.duplicateToEdit"))
+            }
+        }
+        .disabled(!viewModel.canEditActivePreset)
+    }
+
+    @ViewBuilder
+    private func pageRow(for page: PanelPageConfiguration) -> some View {
+        NavigationLink {
+            PanelPageEditorView(pageType: page.pageType, viewModel: viewModel)
+        } label: {
+            HStack {
+                Label(page.pageType.displayName, systemImage: page.pageType.systemImage)
+                Spacer()
+                Text(page.isEnabled
+                    ? String(localized: "common.on")
+                    : String(localized: "common.off"))
+                    .foregroundStyle(.secondary)
+            }
+        }
+    }
+
+    // MARK: - Helpers
+
+    private func syncLocalState() {
+        defaultVisibility = viewModel.panelDefaultVisibility
+    }
+}
+
+#endif

Yattee/Views/Settings/PlayerControls/PlayerControlsSettingsView.swift

@@ -398,6 +398,24 @@ private struct LayoutSectionsSection: View {
                 )
             }
             .disabled(!viewModel.canEditActivePreset)
+
+            // The details panel exists in the iOS and macOS players.
+            #if os(iOS) || os(macOS)
+            NavigationLink {
+                PanelSettingsView(viewModel: viewModel)
+            } label: {
+                HStack {
+                    Label(
+                        String(localized: "settings.playerControls.detailsPanel"),
+                        systemImage: "sidebar.trailing"
+                    )
+                    Spacer()
+                    Text("\(viewModel.enabledPanelPageCount)")
+                        .foregroundStyle(.secondary)
+                }
+            }
+            .disabled(!viewModel.canEditActivePreset)
+            #endif
         } header: {
             Text(String(localized: "settings.playerControls.layoutSections"))
         } footer: {