feat: redesign Pump page with Fluent card layout, bottom snackbar, and RPM chart

- Replace sub-nav + HiddenTabsTabControl with 3-column Fluent card layout:
  PumpCommandsCard (vertical ME/FBKW/PreIn sliders) + DfiCalibrationCard /
  PumpLiveDataCard (KPI tiles + RPM rolling chart + redesigned status bytes) /
  PumpIdentificationCard + DtcCard
- Add PumpTopStripView: pump selector, model badge, CAN + K-Line chips
- Move immobilizer unlock to MainWindow bottom snackbar (UnlockSnackbarView):
  auto-close on success after 3 s, persist on failure with manual Dismiss
- Redesign StatusDisplayView to 2×8 rounded 28px tiles with bit index + tooltip
- Add NullToVisibilityConverter; add SnackbarShell, PumpCard, and related styles
- Delete obsolete views: UnlockProgressDialog, UnlockPanelView,
  PumpIdentificationPanelView, PumpLiveDataView, DfiManageView,
  DtcListView, PumpControlView
- PumpPageViewModel: remove PumpSubPage enum, add RpmChart wired to Root.PumpRpm

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

Converters/NullToVisibilityConverter.cs

@@ -0,0 +1,20 @@
+using System;
+using System.Globalization;
+using System.Windows;
+using System.Windows.Data;
+
+namespace HC_APTBS.Converters
+{
+    /// <summary>
+    /// Returns <see cref="Visibility.Visible"/> when the value is non-null,
+    /// and <see cref="Visibility.Collapsed"/> when the value is null.
+    /// </summary>
+    public sealed class NullToVisibilityConverter : IValueConverter
+    {
+        public object Convert(object? value, Type targetType, object parameter, CultureInfo culture)
+            => value is null ? Visibility.Collapsed : Visibility.Visible;
+
+        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+            => throw new NotSupportedException();
+    }
+}