Add port config, quick-switch toolbar, and dark mode styling

- Add Config button to each monitor for hiding ports, custom labels, and quick-switch selection
- Add quick-switch toolbar at top of popup for one-click input switching
- Add dark mode styling for all controls (buttons, combobox, dropdown items)
- Add loading spinner animation
- Add Exit button in header
- Fix dropdown selection to correctly show current input

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Library/Config/MonitorConfigManager.cs

@@ -0,0 +1,125 @@
+using CMM.Library.Helpers;
+using CMM.Library.ViewModel;
+using System.IO;
+
+namespace CMM.Library.Config;
+
+public static class MonitorConfigManager
+{
+    private static readonly string ConfigFolder = Path.Combine(
+        Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData),
+        "MonitorControl");
+
+    private static readonly string ConfigFile = Path.Combine(ConfigFolder, "config.json");
+
+    private static AppConfig? _cachedConfig;
+
+    public static AppConfig Load()
+    {
+        if (_cachedConfig != null)
+            return _cachedConfig;
+
+        if (!File.Exists(ConfigFile))
+        {
+            _cachedConfig = new AppConfig();
+            return _cachedConfig;
+        }
+
+        try
+        {
+            _cachedConfig = ConfigFile.JsonFormFile<AppConfig>() ?? new AppConfig();
+        }
+        catch
+        {
+            _cachedConfig = new AppConfig();
+        }
+
+        return _cachedConfig;
+    }
+
+    public static void Save(AppConfig config)
+    {
+        _cachedConfig = config;
+        config.FileToJson(ConfigFile);
+    }
+
+    public static MonitorConfig GetMonitorConfig(string serialNumber)
+    {
+        var config = Load();
+        return config.Monitors.FirstOrDefault(m => m.SerialNumber == serialNumber)
+               ?? new MonitorConfig { SerialNumber = serialNumber };
+    }
+
+    public static void SaveMonitorConfig(MonitorConfig monitorConfig)
+    {
+        var config = Load();
+        var existing = config.Monitors.FirstOrDefault(m => m.SerialNumber == monitorConfig.SerialNumber);
+
+        if (existing != null)
+            config.Monitors.Remove(existing);
+
+        config.Monitors.Add(monitorConfig);
+        Save(config);
+    }
+
+    public static List<QuickSwitchItem> GetQuickSwitchItems()
+    {
+        var config = Load();
+        var items = new List<QuickSwitchItem>();
+
+        foreach (var monitor in config.Monitors)
+        {
+            foreach (var port in monitor.Ports.Where(p => p.ShowInQuickSwitch && !p.IsHidden))
+            {
+                items.Add(new QuickSwitchItem
+                {
+                    MonitorSerialNumber = monitor.SerialNumber,
+                    MonitorName = monitor.MonitorName,
+                    PortVcpValue = port.VcpValue,
+                    PortLabel = port.DisplayName
+                });
+            }
+        }
+
+        return items;
+    }
+
+    public static List<InputSourceOption> ApplyConfigToOptions(
+        string serialNumber,
+        List<InputSourceOption> options)
+    {
+        var monitorConfig = GetMonitorConfig(serialNumber);
+
+        if (monitorConfig.Ports.Count == 0)
+            return options;
+
+        var result = new List<InputSourceOption>();
+
+        foreach (var option in options)
+        {
+            var portConfig = monitorConfig.Ports.FirstOrDefault(p => p.VcpValue == option.Value);
+
+            if (portConfig != null)
+            {
+                // Respect hidden setting - don't show hidden ports
+                if (portConfig.IsHidden)
+                    continue;
+
+                if (!string.IsNullOrWhiteSpace(portConfig.CustomLabel))
+                {
+                    result.Add(new InputSourceOption(option.Value, portConfig.CustomLabel));
+                    continue;
+                }
+            }
+
+            result.Add(option);
+        }
+
+        return result;
+    }
+
+    public static void ClearCache()
+    {
+        _cachedConfig = null;
+    }
+}

Library/ViewModel/MonitorConfig.cs

@@ -0,0 +1,44 @@
+namespace CMM.Library.ViewModel;
+
+/// <summary>
+/// Configuration for a single monitor's ports
+/// </summary>
+public class MonitorConfig
+{
+    public string SerialNumber { get; set; } = string.Empty;
+    public string MonitorName { get; set; } = string.Empty;
+    public List<PortConfig> Ports { get; set; } = new();
+}
+
+/// <summary>
+/// Configuration for a single input port
+/// </summary>
+public class PortConfig
+{
+    public int VcpValue { get; set; }
+    public string DefaultName { get; set; } = string.Empty;
+    public string CustomLabel { get; set; } = string.Empty;
+    public bool IsHidden { get; set; }
+    public bool ShowInQuickSwitch { get; set; }
+
+    public string DisplayName => string.IsNullOrWhiteSpace(CustomLabel) ? DefaultName : CustomLabel;
+}
+
+/// <summary>
+/// Quick switch item shown in toolbar
+/// </summary>
+public class QuickSwitchItem
+{
+    public string MonitorSerialNumber { get; set; } = string.Empty;
+    public string MonitorName { get; set; } = string.Empty;
+    public int PortVcpValue { get; set; }
+    public string PortLabel { get; set; } = string.Empty;
+}
+
+/// <summary>
+/// Root configuration object
+/// </summary>
+public class AppConfig
+{
+    public List<MonitorConfig> Monitors { get; set; } = new();
+}