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>

Infrastructure/Pcan/PcanAdapter.cs

@@ -31,7 +31,7 @@ namespace HC_APTBS.Infrastructure.Pcan
 
         // ── State ────────────────────────────────────────────────────────────────
 
-        private readonly TPCANHandle _channel;
+        private TPCANHandle _channel;
         private TPCANBaudrate _baudrate;
         private readonly IAppLogger _log;
 
@@ -75,6 +75,19 @@ namespace HC_APTBS.Infrastructure.Pcan
         /// <inheritdoc/>
         public bool IsConnected => !_stopRead;
 
+        /// <inheritdoc/>
+        public TPCANHandle SelectedChannel
+        {
+            get => _channel;
+            set
+            {
+                if (IsConnected)
+                    throw new System.InvalidOperationException(
+                        "Cannot change the CAN channel while connected. Call Disconnect() first.");
+                _channel = value;
+            }
+        }
+
         // ── Construction ─────────────────────────────────────────────────────────
 
         /// <summary>
@@ -91,6 +104,45 @@ namespace HC_APTBS.Infrastructure.Pcan
             _log = logger;
         }
 
+        // ── ICanService: discovery ────────────────────────────────────────────────
+
+        /// <inheritdoc/>
+        public System.Collections.Generic.IReadOnlyList<AttachedPcanChannel> EnumerateAttachedChannels()
+        {
+            var result = new System.Collections.Generic.List<AttachedPcanChannel>();
+            try
+            {
+                var countStatus = PCANBasic.GetValue(
+                    PCANBasic.PCAN_NONEBUS,
+                    TPCANParameter.PCAN_ATTACHED_CHANNELS_COUNT,
+                    out uint count,
+                    sizeof(uint));
+
+                if (countStatus != TPCANStatus.PCAN_ERROR_OK || count == 0)
+                    return result;
+
+                var buffer = new TPCANChannelInformation[count];
+                var infoStatus = PCANBasic.GetValue(
+                    PCANBasic.PCAN_NONEBUS,
+                    TPCANParameter.PCAN_ATTACHED_CHANNELS,
+                    buffer);
+
+                if (infoStatus != TPCANStatus.PCAN_ERROR_OK)
+                    return result;
+
+                foreach (var ch in buffer)
+                {
+                    if (ch.device_type == TPCANDevice.PCAN_USB)
+                        result.Add(new AttachedPcanChannel(ch.channel_handle, ch.device_name ?? $"PCAN-USB ({ch.channel_handle:X})"));
+                }
+            }
+            catch (Exception ex)
+            {
+                _log.Warning(LogId, $"EnumerateAttachedChannels failed: {ex.Message}");
+            }
+            return result;
+        }
+
         // ── ICanService: lifecycle ────────────────────────────────────────────────
 
         /// <inheritdoc/>