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>

Infrastructure/Pcan/PcanAdapter.cs

@@ -237,9 +237,11 @@ namespace HC_APTBS.Infrastructure.Pcan
             foreach (var param in parameters)
             {
                 if (param.IsReceive) continue;
-                uint raw = (uint)param.GetTransmitValue();
-                msg.DATA[param.ByteH] = (byte)((raw & 0xFF00) >> 8);
-                msg.DATA[param.ByteL] = (byte)(raw & 0x00FF);
+                // Cast to int first so negative values (e.g. FBKW) get proper
+                // two's complement representation in the 16-bit CAN field.
+                ushort raw = unchecked((ushort)(int)param.GetTransmitValue());
+                msg.DATA[param.ByteH] = (byte)(raw >> 8);
+                msg.DATA[param.ByteL] = (byte)(raw & 0xFF);
             }
 
             CurrentStatus = PCANBasic.Write(_channel, ref msg);