feat: Add Print Service Tray application with configuration and queue management

- Implemented PrintQueueService with job counting and snapshot retrieval.
- Created Form1 as the main entry point for the tray application.
- Developed ConfigurationForm for managing printer configurations and document types.
- Added models for printer configuration, queue status requests, and responses.
- Established ConfigurationService for loading and saving printer configurations.
- Introduced ServiceClient for IPC communication with the print service.
- Built TrayApplicationContext for managing the system tray icon and status updates.
- Added TODO.md for tracking remaining work and future enhancements.

PrintServiceTray/Services/ConfigurationService.cs

@@ -0,0 +1,136 @@
+using System.Text.Json;
+using PrintServiceTray.Models;
+
+namespace PrintServiceTray.Services;
+
+public class ConfigurationService
+{
+    private readonly string _globalConfigPath;
+    private readonly string _localConfigPath;
+
+    public ConfigurationService()
+    {
+        // Global config: next to CLI executable (C:\LAAPC or wherever installed)
+        var cliPath = Path.Combine(
+            Environment.GetFolderPath(Environment.SpecialFolder.CommonApplicationData),
+            "LAAPC"
+        );
+        _globalConfigPath = Path.Combine(cliPath, "printer-config.json");
+
+        // Local config: user's AppData
+        var appDataPath = Path.Combine(
+            Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
+            "LAAPC"
+        );
+        Directory.CreateDirectory(appDataPath);
+        _localConfigPath = Path.Combine(appDataPath, "printer-config.json");
+    }
+
+    /// <summary>
+    /// Load configuration (local overrides global)
+    /// </summary>
+    public PrinterConfiguration Load()
+    {
+        var config = new PrinterConfiguration();
+
+        // Load global first
+        if (File.Exists(_globalConfigPath))
+        {
+            try
+            {
+                var json = File.ReadAllText(_globalConfigPath);
+                var globalConfig = JsonSerializer.Deserialize<PrinterConfiguration>(json);
+                if (globalConfig != null)
+                {
+                    config = globalConfig;
+                }
+            }
+            catch { }
+        }
+
+        // Load local and merge/override
+        if (File.Exists(_localConfigPath))
+        {
+            try
+            {
+                var json = File.ReadAllText(_localConfigPath);
+                var localConfig = JsonSerializer.Deserialize<PrinterConfiguration>(json);
+                if (localConfig != null)
+                {
+                    // Merge: local overrides global for matching document types
+                    foreach (var kvp in localConfig.DocumentTypes)
+                    {
+                        config.DocumentTypes[kvp.Key] = kvp.Value;
+                    }
+                }
+            }
+            catch { }
+        }
+
+        return config;
+    }
+
+    /// <summary>
+    /// Save configuration to global or local
+    /// </summary>
+    public void Save(PrinterConfiguration config, bool saveGlobal)
+    {
+        var path = saveGlobal ? _globalConfigPath : _localConfigPath;
+        
+        // Ensure directory exists
+        var directory = Path.GetDirectoryName(path);
+        if (!string.IsNullOrEmpty(directory))
+        {
+            Directory.CreateDirectory(directory);
+        }
+
+        var options = new JsonSerializerOptions
+        {
+            WriteIndented = true
+        };
+        var json = JsonSerializer.Serialize(config, options);
+        File.WriteAllText(path, json);
+    }
+
+    /// <summary>
+    /// Get all installed printers
+    /// </summary>
+    public List<string> GetInstalledPrinters()
+    {
+        var printers = new List<string>();
+        try
+        {
+            foreach (string printerName in System.Drawing.Printing.PrinterSettings.InstalledPrinters)
+            {
+                printers.Add(printerName);
+            }
+        }
+        catch { }
+        return printers;
+    }
+
+    /// <summary>
+    /// Get available trays for a printer
+    /// </summary>
+    public List<(int Number, string Name)> GetPrinterTrays(string printerName)
+    {
+        var trays = new List<(int, string)>();
+        try
+        {
+            var printerSettings = new System.Drawing.Printing.PrinterSettings
+            {
+                PrinterName = printerName
+            };
+
+            foreach (System.Drawing.Printing.PaperSource source in printerSettings.PaperSources)
+            {
+                trays.Add((source.RawKind, source.SourceName));
+            }
+        }
+        catch { }
+        return trays;
+    }
+
+    public string GlobalConfigPath => _globalConfigPath;
+    public string LocalConfigPath => _localConfigPath;
+}