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>

Services/ICanService.cs

@@ -41,6 +41,22 @@ namespace HC_APTBS.Services
         /// <summary>True when the CAN read thread is running and the channel is open.</summary>
         bool IsConnected { get; }
 
+        /// <summary>
+        /// The PCAN channel handle that will be used on the next <see cref="Connect"/> call.
+        /// Defaults to the channel supplied at construction.
+        /// Throws <see cref="System.InvalidOperationException"/> when set while <see cref="IsConnected"/> is true.
+        /// </summary>
+        TPCANHandle SelectedChannel { get; set; }
+
+        // ── Discovery ─────────────────────────────────────────────────────────────
+
+        /// <summary>
+        /// Enumerates PCAN USB channels that are physically attached to the system.
+        /// Returns an empty list if no adapters are connected or if the PCAN-Basic DLL
+        /// is unavailable. Never throws.
+        /// </summary>
+        System.Collections.Generic.IReadOnlyList<AttachedPcanChannel> EnumerateAttachedChannels();
+
         // ── Lifecycle ─────────────────────────────────────────────────────────────
 
         /// <summary>

Services/IKwpService.cs

@@ -110,6 +110,12 @@ namespace HC_APTBS.Services
         /// </summary>
         string? DetectKLinePort();
 
+        /// <summary>
+        /// The FTDI serial number of the device that is currently holding an open
+        /// K-Line session, or <see langword="null"/> when no session is active.
+        /// </summary>
+        string? ConnectedPort { get; }
+
         // ── Mid-read notifications ────────────────────────────────────────────
 
         /// <summary>

Services/Impl/KwpService.cs

@@ -73,6 +73,9 @@ namespace HC_APTBS.Services.Impl
         /// <inheritdoc/>
         public KLineConnectionState KLineState => _kLineState;
 
+        /// <inheritdoc/>
+        public string? ConnectedPort => _connectedPort;
+
         // ── Constructor ───────────────────────────────────────────────────────────
 
         /// <param name="logger">Application logger.</param>
@@ -289,7 +292,7 @@ namespace HC_APTBS.Services.Impl
                 Report(85, "Reading fault codes...");
                 kwp.KeepAlive();
                 var faultCodes = kwp.ReadFaultCodes();
-                result[KlineKeys.Errors] = faultCodes.Count > 0
+                result[KlineKeys.Errors] = faultCodes?.Count > 0
                     ? string.Join(Environment.NewLine, faultCodes)
                     : KlineKeys.NoErrors;
 
@@ -418,7 +421,7 @@ namespace HC_APTBS.Services.Impl
                 Report(85, "Reading fault codes...");
                 kwp.KeepAlive();
                 var faultCodes = kwp.ReadFaultCodes();
-                result[KlineKeys.Errors] = faultCodes.Count > 0
+                result[KlineKeys.Errors] = faultCodes?.Count > 0
                     ? string.Join(Environment.NewLine, faultCodes)
                     : KlineKeys.NoErrors;
 
@@ -621,14 +624,15 @@ namespace HC_APTBS.Services.Impl
 
             return await Task.Run(() =>
             {
+                _busLock.Wait();
                 try
                 {
                     _log.Info(LogId, "TryFastUnlock: sending unlock command over K-Line");
-                    var packets = _sessionKwp.SendCustom(
+                    var packets = _sessionKwp!.SendCustom(
                         new List<byte> { 0x02, 0x88, 0x02, 0x03, 0xA8, 0x01, 0x00 });
 
                     bool nak = packets.Count == 1
-                        && packets[0] is HC_APTBS.Infrastructure.Kwp.Packets.NakPacket;
+                        && packets[0] is NakPacket;
 
                     _log.Info(LogId, $"TryFastUnlock: {(nak ? "NAK — pump rejected" : "ACK — pump unlocked")}");
                     return !nak;
@@ -638,6 +642,10 @@ namespace HC_APTBS.Services.Impl
                     _log.Warning(LogId, $"TryFastUnlock failed: {ex.Message}");
                     return false;
                 }
+                finally
+                {
+                    _busLock.Release();
+                }
             });
         }
 
@@ -686,33 +694,33 @@ namespace HC_APTBS.Services.Impl
         {
             while (!ct.IsCancellationRequested)
             {
+                // Non-blocking try-acquire: if an operation holds the lock
+                // we skip this cycle — the operation itself keeps the bus alive.
+                if (await _busLock.WaitAsync(0, ct))
+                {
+                    try
+                    {
+                        _sessionKwp!.KeepAlive();
+                    }
+                    catch (OperationCanceledException) { return; }
+                    catch (Exception ex)
+                    {
+                        _log.Error(LogId, $"Keep-alive failed: {ex.Message}");
+                        CleanupSession();
+                        SetState(KLineConnectionState.Failed);
+                        return;
+                    }
+                    finally
+                    {
+                        _busLock.Release();
+                    }
+                }
+
                 try
                 {
                     await Task.Delay(KeepAliveIntervalMs, ct);
                 }
                 catch (OperationCanceledException) { return; }
-
-                // Non-blocking try-acquire: if an operation holds the lock
-                // we skip this cycle — the operation itself keeps the bus alive.
-                if (!await _busLock.WaitAsync(0, ct))
-                    continue;
-
-                try
-                {
-                    _sessionKwp!.KeepAlive();
-                }
-                catch (OperationCanceledException) { return; }
-                catch (Exception ex)
-                {
-                    _log.Error(LogId, $"Keep-alive failed: {ex.Message}");
-                    CleanupSession();
-                    SetState(KLineConnectionState.Failed);
-                    return;
-                }
-                finally
-                {
-                    _busLock.Release();
-                }
             }
         }
 
@@ -746,7 +754,7 @@ namespace HC_APTBS.Services.Impl
                 var codes = _sessionKwp.ReadFaultCodes();
                 _sessionKwp.KeepAlive();
                 Report(100, "Done.");
-                return codes.Count > 0
+                return codes?.Count > 0
                     ? string.Join(Environment.NewLine, codes)
                     : KlineKeys.NoErrors;
             }
@@ -773,7 +781,7 @@ namespace HC_APTBS.Services.Impl
                 var codes = _sessionKwp.ReadFaultCodes();
                 _sessionKwp.KeepAlive();
                 Report(100, "Done.");
-                return codes.Count > 0
+                return codes?.Count > 0
                     ? string.Join(Environment.NewLine, codes)
                     : KlineKeys.NoErrors;
             }