feat: page-based navigation shell + Tests page wizard

Replace the monolithic MainWindow with a SelectedPage-driven shell
(Dashboard / Pump / Bench / Tests / Results / Settings). The Tests
page gets the Plan -> Preconditions -> Running -> Done wizard from
ui-structure.md \u00a74, backed by a 7-item precondition gate and
shared sub-views (PhaseCardView / TestSectionView / GraphicIndicatorView)
extracted from the now-deleted monolithic TestPanelView.

New VMs / views:
- Tests wizard: TestPreconditions, PhaseCard, GraphicIndicator,
  TestSection, TestPlan, TestRunning, TestDone
- Dashboard panels: DashboardConnection, DashboardReadings,
  DashboardAlarms, InterlockBanner, ResultHistory
- Pump / bench panels: PumpIdentificationPanel, PumpLiveData,
  UnlockPanel, BenchDriveControl, BenchReadings, RelayBank,
  TemperatureControl, DtcList, AuthGate
- Dialogs: generic ConfirmDialog, UserManageDialog, UserPromptDialog

Supporting changes:
- IsOilPumpOn exposed on MainViewModel for precondition evaluation
- RequiresAuth added to TestDefinition (XML round-trip)
- BipStatusDefinition + CompletedTestRun models
- ~35 new Test.* localization keys (en + es)
- Settings moved from modal dialog to full page
- Pause / Retry / Skip stubs in TestRunningView; full spec in
  docs/gap-test-running-controls.md for follow-up implementation
- docs/ui-structure.md captures the wizard design

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Views/UserControls/AuthGateView.xaml.cs

@@ -0,0 +1,31 @@
+using System.Windows;
+using System.Windows.Controls;
+
+namespace HC_APTBS.Views.UserControls
+{
+    /// <summary>
+    /// A gated container that shows <see cref="GatedContent"/> only after the operator
+    /// authenticates via <c>AuthGateViewModel</c>. DataContext is
+    /// <c>AuthGateViewModel</c>.
+    /// </summary>
+    public partial class AuthGateView : UserControl
+    {
+        /// <summary>The content to show once the gate unlocks.</summary>
+        public static readonly DependencyProperty GatedContentProperty =
+            DependencyProperty.Register(
+                nameof(GatedContent), typeof(object), typeof(AuthGateView),
+                new PropertyMetadata(null));
+
+        /// <summary>Gets or sets the content displayed when the gate is unlocked.</summary>
+        public object? GatedContent
+        {
+            get => GetValue(GatedContentProperty);
+            set => SetValue(GatedContentProperty, value);
+        }
+
+        public AuthGateView()
+        {
+            InitializeComponent();
+        }
+    }
+}