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>

Models/CanBusParameter.cs

@@ -105,6 +105,19 @@ namespace HC_APTBS.Models
         /// </summary>
         public double Alpha { get; set; } = 1.0;
 
+        // ── Runtime-warning plumbing ──────────────────────────────────────────────
+
+        /// <summary>
+        /// Static logging hook invoked when <see cref="GetTransformResult"/> encounters
+        /// a zero denominator. Wired at app startup to <c>IAppLogger.Warning</c>.
+        /// Left null keeps the Models layer DI-free and testable.
+        /// Signature: (source, message).
+        /// </summary>
+        public static Action<string, string>? WarningLogger { get; set; }
+
+        /// <summary>Set once per instance after the first zero-denominator warning, to prevent hot-loop log spam.</summary>
+        private bool _warnedDenomZero;
+
         // ── Convenience alias kept for cross-file compatibility ───────────────────
 
         /// <summary>Alias for <see cref="MessageId"/> — used by legacy call sites.</summary>
@@ -144,16 +157,40 @@ namespace HC_APTBS.Models
         /// <summary>
         /// Applies the P1–P6 rational transfer function to <see cref="Value"/>.
         /// Used only by pump params (<see cref="UseLegacyTransform"/> = true).
+        /// Returns 0 and warns once if the denominator is zero.
         /// </summary>
         public double GetTransformResult()
         {
             if (IsReceive)
             {
-                return (-P2 - P3 * P5 - P4 * P6 + P4 * Value)
-                     / (P1 + P3 * P5 + P3 * P6 - P3 * Value);
+                double denom = P1 + P3 * P5 + P3 * P6 - P3 * Value;
+                if (denom == 0.0)
+                {
+                    if (!_warnedDenomZero)
+                    {
+                        WarningLogger?.Invoke(nameof(CanBusParameter),
+                            $"Zero denominator for '{Name}' (receive). Returning 0.");
+                        _warnedDenomZero = true;
+                    }
+                    return 0.0;
+                }
+                return (-P2 - P3 * P5 - P4 * P6 + P4 * Value) / denom;
             }
 
-            return ((P1 * Value + P2) / (P3 * Value + P4)) + P5 + P6;
+            {
+                double denom = P3 * Value + P4;
+                if (denom == 0.0)
+                {
+                    if (!_warnedDenomZero)
+                    {
+                        WarningLogger?.Invoke(nameof(CanBusParameter),
+                            $"Zero denominator for '{Name}' (transmit). Returning 0.");
+                        _warnedDenomZero = true;
+                    }
+                    return 0.0;
+                }
+                return ((P1 * Value + P2) / denom) + P5 + P6;
+            }
         }
 
         /// <summary>
@@ -185,13 +222,22 @@ namespace HC_APTBS.Models
         /// </summary>
         public static CanBusParameter FromXml(XElement xe)
         {
+            string name = xe.Name.LocalName;
+            ushort byteh = ushort.Parse(xe.Attribute("byteh")?.Value ?? "0");
+            ushort bytel = ushort.Parse(xe.Attribute("bytel")?.Value ?? "0");
+            if (byteh > 7 || bytel > 7)
+            {
+                throw new ArgumentOutOfRangeException(nameof(xe),
+                    $"Param '{name}': byteh={byteh} bytel={bytel} out of 0-7.");
+            }
+
             var p = new CanBusParameter
             {
-                Name      = xe.Name.LocalName,
+                Name      = name,
                 MessageId = uint.Parse(xe.Attribute("busid")?.Value ?? "0",
                                 NumberStyles.HexNumber),
-                ByteH     = ushort.Parse(xe.Attribute("byteh")?.Value ?? "0"),
-                ByteL     = ushort.Parse(xe.Attribute("bytel")?.Value ?? "0"),
+                ByteH     = byteh,
+                ByteL     = bytel,
                 Type      = int.Parse(xe.Attribute("type")?.Value ?? "0"),
                 IsReceive = !string.Equals(xe.Attribute("send")?.Value, "true",
                                 StringComparison.OrdinalIgnoreCase),