Add Debug page and fix BLE communication issues

Major changes:
- Added Debug tab with real-time message logging and hex viewer
- Implemented timed data logging ($UMTDL command) per API v1.3
- Fixed BLE message parsing to handle notifications without line endings
- Added Schema 2 support (22-field timed logging packets)
- Updated Maglink BLE UUIDs (fff0/fff1/fff2)
- Added connection timeout (10s) to prevent hanging on unavailable devices
- Added connection status display and manual push-button logging trigger
- Improved retry logging with attempt numbers and delays
- Added console window allocation for Windows debug output
- Added BLE disconnect on app close

Bug fixes:
- Fixed device name filtering for Maglink (ML-* prefix)
- Fixed RtkGps enum reference in DeviceScanViewModel
- Fixed DebugMessage namespace (moved to Models)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

FieldLogger/Services/UmReceiverService.cs

@@ -10,7 +10,7 @@ namespace FieldLogger.Services;
 /// </summary>
 public sealed class UmReceiverService : IAsyncDisposable
 {
-    // UM Receiver BLE External Logging API v1.2:
+    // UM Receiver BLE External Logging API v1.3:
     // serial port service with notify (RX) and write-no-response (TX) characteristics.
     public static readonly Guid ServiceUuid = Guid.Parse("554d0000-261f-677e-a6f1-54c57aa996d4");
     public static readonly Guid NotifyUuid = Guid.Parse("554d0001-261f-677e-a6f1-54c57aa996d4");
@@ -23,11 +23,14 @@ public sealed class UmReceiverService : IAsyncDisposable
     public bool IsConnected => _client.IsConnected;
     public string? DeviceName => _client.DeviceName;
 
-    /// <summary>Raised when the operator presses the log button on the receiver.</summary>
+    /// <summary>Raised when the operator presses the log button on the receiver or timed logging triggers.</summary>
     public event EventHandler<UmLogPacket>? PacketReceived;
     public event EventHandler<UmDeviceInfo>? DeviceInfoReceived;
     public event EventHandler? Disconnected;
 
+    /// <summary>Raised for all received lines (for debugging).</summary>
+    public event EventHandler<string>? LineReceived;
+
     public UmReceiverService(ILogger<UmReceiverService> logger)
     {
         _logger = logger;
@@ -54,12 +57,31 @@ public sealed class UmReceiverService : IAsyncDisposable
     public Task DisableLoggingAsync(CancellationToken cancellationToken = default)
         => _client.WriteLineAsync("$UMPBDL,0", cancellationToken);
 
+    /// <summary>
+    /// Enables timed data logging at the specified period.
+    /// </summary>
+    /// <param name="logPeriod">Log period multiplier (period = logPeriod * 100ms). Valid: 10-100.</param>
+    /// <param name="cancellationToken">Cancellation token.</param>
+    public Task EnableTimedLoggingAsync(int logPeriod, CancellationToken cancellationToken = default)
+    {
+        if (logPeriod < 10 || logPeriod > 100)
+            throw new ArgumentOutOfRangeException(nameof(logPeriod), "Log period must be between 10 and 100 (1s to 10s)");
+        return _client.WriteLineAsync($"$UMETDL,{logPeriod}", cancellationToken);
+    }
+
+    /// <summary>Disables timed data logging.</summary>
+    public Task DisableTimedLoggingAsync(CancellationToken cancellationToken = default)
+        => _client.WriteLineAsync("$UMETDL,0", cancellationToken);
+
     public Task DisconnectAsync() => _client.DisconnectAsync();
 
     private void OnLineReceived(object? sender, string line)
     {
         _logger.LogDebug("UM rx: {Line}", line);
 
+        // Notify debug listeners of all lines
+        LineReceived?.Invoke(this, line);
+
         // Bare command acknowledgements.
         var trimmed = line.Trim();
         if (trimmed.Equals("OK", StringComparison.OrdinalIgnoreCase) ||