feat: redesign dashboard with Fluent KPI tiles, connection strip, and devices column

- Replace LCD-style readings with a 3×2 KPI tile grid (Fluent card surfaces, 52pt values)
- Add persistent top connection strip with horizontal chips + pump name badge
- Add elapsed test timer (DispatcherTimer, mm:ss) to Test Summary card
- Restyle Test Summary and Active Alarms with Fluent brushes/iconography
- Add Devices column (CAN / K-Line / Bench tiles) between KPI grid and test/alarms
  - Enumerates attached PCAN USB channels via PCAN_ATTACHED_CHANNELS API
  - Enumerates FTDI K-Line adapters via existing FtdiInterface helpers
  - Click to connect/disconnect; confirmation dialog when session active or test running
  - Hover tint: blue = will connect, red = will disconnect; Bench row is read-only stub
- Extend ICanService with SelectedChannel + EnumerateAttachedChannels()
- Expose IKwpService.ConnectedPort for active session device tracking
- Add DeviceRow button style with MultiDataTrigger hover colour logic
- Add 30+ new localization keys (ES + EN) for KPI labels, devices, confirmations

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

App.xaml.cs

@@ -1,5 +1,7 @@
 using System.Windows;
+using System.Windows.Media;
 using HC_APTBS.Infrastructure.Logging;
+using Wpf.Ui.Appearance;
 using HC_APTBS.Infrastructure.Pcan;
 using HC_APTBS.Models;
 using HC_APTBS.Services;
@@ -27,6 +29,10 @@ public partial class App : Application
     {
         base.OnStartup(e);
 
+        // Apply WPF-UI theme and accent colour before any UI is constructed.
+        ApplicationThemeManager.Apply(ApplicationTheme.Light);
+        ApplicationAccentColorManager.Apply(Color.FromRgb(0x21, 0x96, 0xF3));
+
         var services = new ServiceCollection();
         ConfigureServices(services);
         _serviceProvider = services.BuildServiceProvider();