feat: Add Electron desktop application wrapper

- Create electron-main.js with window, tray, and menu management
- Add Electron and electron-builder dependencies
- Configure build settings for Windows
- Add npm scripts for electron and build
- Desktop app features: system tray, menu bar, auto-start server

electron-main.js

@@ -0,0 +1,211 @@
+const { app, BrowserWindow, Tray, Menu, ipcMain } = require('electron');
+const path = require('path');
+const express = require('express');
+const server = require('./server');
+
+let mainWindow;
+let tray;
+let isQuitting = false;
+
+// Express server instance (from server.js)
+const PORT = process.env.PORT || 3000;
+
+function createWindow() {
+    mainWindow = new BrowserWindow({
+        width: 1200,
+        height: 900,
+        minWidth: 800,
+        minHeight: 600,
+        icon: path.join(__dirname, 'public/Logo.png'),
+        webPreferences: {
+            nodeIntegration: false,
+            contextIsolation: true,
+            enableRemoteModule: false
+        },
+        title: 'Advanced SMTP Tester',
+        backgroundColor: '#0f172a',
+        show: false // Don't show until ready
+    });
+
+    // Load the app
+    mainWindow.loadURL(`http://localhost:${PORT}`);
+
+    // Show window when ready
+    mainWindow.once('ready-to-show', () => {
+        mainWindow.show();
+    });
+
+    // Handle window close
+    mainWindow.on('close', (event) => {
+        if (!isQuitting) {
+            event.preventDefault();
+            mainWindow.hide();
+            return false;
+        }
+    });
+
+    mainWindow.on('closed', () => {
+        mainWindow = null;
+    });
+
+    // Create application menu
+    createMenu();
+}
+
+function createTray() {
+    tray = new Tray(path.join(__dirname, 'public/Logo.png'));
+
+    const contextMenu = Menu.buildFromTemplate([
+        {
+            label: 'Show App',
+            click: () => {
+                mainWindow.show();
+            }
+        },
+        {
+            label: 'Hide App',
+            click: () => {
+                mainWindow.hide();
+            }
+        },
+        { type: 'separator' },
+        {
+            label: 'Quit',
+            click: () => {
+                isQuitting = true;
+                app.quit();
+            }
+        }
+    ]);
+
+    tray.setToolTip('Advanced SMTP Tester');
+    tray.setContextMenu(contextMenu);
+
+    // Double click to show/hide
+    tray.on('double-click', () => {
+        if (mainWindow.isVisible()) {
+            mainWindow.hide();
+        } else {
+            mainWindow.show();
+        }
+    });
+}
+
+function createMenu() {
+    const template = [
+        {
+            label: 'File',
+            submenu: [
+                {
+                    label: 'Minimize to Tray',
+                    accelerator: 'CmdOrCtrl+H',
+                    click: () => {
+                        mainWindow.hide();
+                    }
+                },
+                { type: 'separator' },
+                {
+                    label: 'Quit',
+                    accelerator: 'CmdOrCtrl+Q',
+                    click: () => {
+                        isQuitting = true;
+                        app.quit();
+                    }
+                }
+            ]
+        },
+        {
+            label: 'Edit',
+            submenu: [
+                { role: 'undo' },
+                { role: 'redo' },
+                { type: 'separator' },
+                { role: 'cut' },
+                { role: 'copy' },
+                { role: 'paste' },
+                { role: 'selectAll' }
+            ]
+        },
+        {
+            label: 'View',
+            submenu: [
+                { role: 'reload' },
+                { role: 'forceReload' },
+                { role: 'toggleDevTools' },
+                { type: 'separator' },
+                { role: 'resetZoom' },
+                { role: 'zoomIn' },
+                { role: 'zoomOut' },
+                { type: 'separator' },
+                { role: 'togglefullscreen' }
+            ]
+        },
+        {
+            label: 'Help',
+            submenu: [
+                {
+                    label: 'About',
+                    click: async () => {
+                        const { shell } = require('electron');
+                        await shell.openExternal('https://github.com/DeNNiiInc/Advanced-Smtp-Tester');
+                    }
+                },
+                {
+                    label: 'Documentation',
+                    click: async () => {
+                        const { shell } = require('electron');
+                        await shell.openExternal('https://github.com/DeNNiiInc/Advanced-Smtp-Tester#readme');
+                    }
+                }
+            ]
+        }
+    ];
+
+    const menu = Menu.buildFromTemplate(template);
+    Menu.setApplicationMenu(menu);
+}
+
+// Wait for server to be ready before creating window
+function waitForServer(callback) {
+    const http = require('http');
+    const checkServer = () => {
+        http.get(`http://localhost:${PORT}`, (res) => {
+            callback();
+        }).on('error', () => {
+            setTimeout(checkServer, 100);
+        });
+    };
+    checkServer();
+}
+
+// App lifecycle
+app.whenReady().then(() => {
+    // Server is already started by requiring ./server.js
+    // Wait for it to be ready
+    waitForServer(() => {
+        createWindow();
+        createTray();
+    });
+
+    app.on('activate', () => {
+        if (BrowserWindow.getAllWindows().length === 0) {
+            createWindow();
+        } else {
+            mainWindow.show();
+        }
+    });
+});
+
+app.on('window-all-closed', () => {
+    // Don't quit on window close, keep running in tray
+    // User must explicitly quit from tray menu
+});
+
+app.on('before-quit', () => {
+    isQuitting = true;
+});
+
+// Handle app quit
+app.on('will-quit', () => {
+    // Cleanup if needed
+});