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>

MainWindow.xaml.cs

@@ -1,6 +1,7 @@
 using System.ComponentModel;
 using System.Windows;
 using HC_APTBS.ViewModels;
+using Wpf.Ui.Controls;
 
 namespace HC_APTBS;
 
@@ -8,7 +9,7 @@ namespace HC_APTBS;
 /// Code-behind for MainWindow — minimal: sets DataContext and forwards the
 /// Closing event to a ViewModel command if needed.
 /// </summary>
-public partial class MainWindow : Window
+public partial class MainWindow : FluentWindow
 {
     public MainWindow(MainViewModel viewModel)
     {