feat: add system tray with quick actions and minimize-to-tray

System tray:
- Always-visible tray icon with context menu
- Quick Scratchpad action from tray (triggers session creation
  via IPC bridge to renderer)
- Running session count in tray tooltip and menu
- Click tray icon to show/focus window
- Quit option in tray menu

Minimize to tray:
- New 'Minimize to tray on close' toggle in Settings > Appearance
- When enabled, closing the window hides to tray instead of
  quitting (configurable per-user, default off)
- macOS: hides dock icon when minimized to tray
- Proper force-quit handling (Cmd+Q on macOS, tray Quit)

Full IPC contract chain:
- minimizeToTray setting in WorkspaceSettings
- setMinimizeToTray channel + ElectronApi method
- Preload bridge, service handler, IPC registration
- Preserved through workspace normalization

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/main/index.ts

@@ -5,11 +5,13 @@ import { registerIpcHandlers } from '@main/ipc/registerIpcHandlers';
 import { AryxAppService } from '@main/AryxAppService';
 import { createMainWindow } from '@main/windows/createMainWindow';
 import { applyTitleBarTheme } from '@main/windows/titleBarTheme';
+import { SystemTray, setupCloseToTray, showAndFocusWindow } from '@main/services/systemTray';
 
 const { app, BrowserWindow } = electron;
 
 let mainWindow: BrowserWindowType | undefined;
 let appService: AryxAppService | undefined;
+let systemTray: SystemTray | undefined;
 
 async function bootstrap(): Promise<void> {
   appService = new AryxAppService();
@@ -21,6 +23,29 @@ async function bootstrap(): Promise<void> {
   const workspace = await appService.loadWorkspace();
   applyTitleBarTheme(mainWindow, workspace.settings.theme);
 
+  // Set up system tray
+  systemTray = new SystemTray({
+    onShowWindow: showAndFocusWindow,
+    onCreateScratchpad: () => {
+      showAndFocusWindow();
+      mainWindow?.webContents.send('tray:create-scratchpad');
+    },
+    onQuit: () => app.quit(),
+  });
+  systemTray.create();
+  systemTray.updateRunningCount(workspace);
+
+  // Intercept close to hide to tray when the setting is enabled
+  setupCloseToTray(mainWindow, () => {
+    const currentWorkspace = appService?.getCachedWorkspace();
+    return currentWorkspace?.settings.minimizeToTray === true;
+  });
+
+  // Keep tray status in sync when workspace changes
+  appService.on('workspace-updated', (updatedWorkspace) => {
+    systemTray?.updateRunningCount(updatedWorkspace);
+  });
+
   if (!app.isPackaged) {
     mainWindow.webContents.openDevTools({ mode: 'detach' });
   }
@@ -29,17 +54,25 @@ async function bootstrap(): Promise<void> {
 app.whenReady().then(bootstrap);
 
 app.on('window-all-closed', () => {
-  if (process.platform !== 'darwin') {
-    app.quit();
-  }
+  // When minimize-to-tray is enabled, don't quit on window close
+  if (process.platform === 'darwin') return;
+
+  const windows = BrowserWindow.getAllWindows();
+  const allHidden = windows.length > 0 && windows.every((w) => !w.isVisible());
+  if (allHidden) return;
+
+  app.quit();
 });
 
 app.on('activate', async () => {
   if (BrowserWindow.getAllWindows().length === 0) {
     await bootstrap();
+  } else {
+    showAndFocusWindow();
   }
 });
 
 app.on('before-quit', async () => {
+  systemTray?.dispose();
   await appService?.dispose();
 });