Add electron-updater auto-update support

- Install electron-updater package
- Configure GitHub releases publish settings
- Create AppUpdater class with full update lifecycle
- Integrate auto-update into main.js
- Add comprehensive documentation (AUTO-UPDATES.md, TESTING-UPDATES.md)
- Set up dev-app-update.yml for testing

backend/appUpdater.js

@@ -0,0 +1,120 @@
+const { autoUpdater } = require('electron-updater');
+const { app } = require('electron');
+const logger = require('./logger');
+
+class AppUpdater {
+  constructor(mainWindow) {
+    this.mainWindow = mainWindow;
+    this.setupAutoUpdater();
+  }
+
+  setupAutoUpdater() {
+    // Enable dev mode for testing (reads dev-app-update.yml)
+    // Only enable in development, not in production builds
+    if (process.env.NODE_ENV === 'development' || !app.isPackaged) {
+      autoUpdater.forceDevUpdateConfig = true;
+      console.log('Dev update mode enabled - using dev-app-update.yml');
+    }
+
+    // Configure logger for electron-updater
+    // Create a compatible logger interface
+    autoUpdater.logger = {
+      info: (...args) => logger.info(...args),
+      warn: (...args) => logger.warn(...args),
+      error: (...args) => logger.error(...args),
+      debug: (...args) => logger.log(...args)
+    };
+
+    // Auto download updates
+    autoUpdater.autoDownload = true;
+    // Auto install on quit (after download)
+    autoUpdater.autoInstallOnAppQuit = true;
+
+    // Event handlers
+    autoUpdater.on('checking-for-update', () => {
+      console.log('Checking for updates...');
+      if (this.mainWindow && !this.mainWindow.isDestroyed()) {
+        this.mainWindow.webContents.send('update-checking');
+      }
+    });
+
+    autoUpdater.on('update-available', (info) => {
+      console.log('Update available:', info.version);
+      if (this.mainWindow && !this.mainWindow.isDestroyed()) {
+        this.mainWindow.webContents.send('update-available', {
+          version: info.version,
+          releaseName: info.releaseName,
+          releaseNotes: info.releaseNotes
+        });
+      }
+    });
+
+    autoUpdater.on('update-not-available', (info) => {
+      console.log('Update not available. Current version is latest.');
+      if (this.mainWindow && !this.mainWindow.isDestroyed()) {
+        this.mainWindow.webContents.send('update-not-available', {
+          version: info.version
+        });
+      }
+    });
+
+    autoUpdater.on('error', (err) => {
+      console.error('Error in auto-updater:', err);
+      if (this.mainWindow && !this.mainWindow.isDestroyed()) {
+        this.mainWindow.webContents.send('update-error', {
+          message: err.message
+        });
+      }
+    });
+
+    autoUpdater.on('download-progress', (progressObj) => {
+      const message = `Download speed: ${progressObj.bytesPerSecond} - Downloaded ${progressObj.percent}% (${progressObj.transferred}/${progressObj.total})`;
+      console.log(message);
+      if (this.mainWindow && !this.mainWindow.isDestroyed()) {
+        this.mainWindow.webContents.send('update-download-progress', {
+          percent: progressObj.percent,
+          bytesPerSecond: progressObj.bytesPerSecond,
+          transferred: progressObj.transferred,
+          total: progressObj.total
+        });
+      }
+    });
+
+    autoUpdater.on('update-downloaded', (info) => {
+      console.log('Update downloaded:', info.version);
+      if (this.mainWindow && !this.mainWindow.isDestroyed()) {
+        this.mainWindow.webContents.send('update-downloaded', {
+          version: info.version,
+          releaseName: info.releaseName,
+          releaseNotes: info.releaseNotes
+        });
+      }
+    });
+  }
+
+  checkForUpdatesAndNotify() {
+    // Check for updates and notify if available
+    autoUpdater.checkForUpdatesAndNotify().catch(err => {
+      console.error('Failed to check for updates:', err);
+    });
+  }
+
+  checkForUpdates() {
+    // Manual check for updates (returns promise)
+    return autoUpdater.checkForUpdates();
+  }
+
+  quitAndInstall() {
+    // Quit and install the update
+    autoUpdater.quitAndInstall(false, true);
+  }
+
+  getUpdateInfo() {
+    return {
+      currentVersion: app.getVersion(),
+      updateAvailable: false
+    };
+  }
+}
+
+module.exports = AppUpdater;