Initial commit: NFC Actions Windows tray application

Implement PC/SC-based NFC card reader monitoring application with WPF UI. Features include:
- System tray integration with single-click to open main window
- Dynamic reader detection and management with enable/disable per reader
- NDEF payload extraction supporting Type 2 and Type 4 tags
- Auto-detection of block sizes (4-byte vs 16-byte) for different reader types
- Configurable actions: copy to clipboard, launch URLs, keyboard input simulation
- URI record type detection - only launches browser for actual URI records
- Real-time activity logging with color-coded levels (Debug, Info, Warning, Error)
- File-based debug logging for troubleshooting
- Settings persistence between sessions
- Dangerous Things branding with custom icons and clickable logo

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

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

NfcActions/Services/SettingsService.cs

@@ -0,0 +1,53 @@
+using System;
+using System.IO;
+using System.Text.Json;
+using NfcActions.Models;
+
+namespace NfcActions.Services;
+
+public class SettingsService
+{
+    private readonly string _settingsPath;
+
+    public SettingsService()
+    {
+        var appDataPath = Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData);
+        var appFolder = Path.Combine(appDataPath, "NfcActions");
+        Directory.CreateDirectory(appFolder);
+        _settingsPath = Path.Combine(appFolder, "settings.json");
+    }
+
+    public AppSettings Load()
+    {
+        try
+        {
+            if (File.Exists(_settingsPath))
+            {
+                var json = File.ReadAllText(_settingsPath);
+                return JsonSerializer.Deserialize<AppSettings>(json) ?? new AppSettings();
+            }
+        }
+        catch (Exception)
+        {
+            // Failed to load settings, return defaults
+        }
+
+        return new AppSettings();
+    }
+
+    public void Save(AppSettings settings)
+    {
+        try
+        {
+            var json = JsonSerializer.Serialize(settings, new JsonSerializerOptions
+            {
+                WriteIndented = true
+            });
+            File.WriteAllText(_settingsPath, json);
+        }
+        catch (Exception)
+        {
+            // Failed to save settings
+        }
+    }
+}