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/preload/index.ts

@@ -27,6 +27,7 @@ const api: ElectronApi = {
   setTheme: (theme) => ipcRenderer.invoke(ipcChannels.setTheme, theme),
   setTerminalHeight: (input) => ipcRenderer.invoke(ipcChannels.setTerminalHeight, input),
   setNotificationsEnabled: (enabled) => ipcRenderer.invoke(ipcChannels.setNotificationsEnabled, enabled),
+  setMinimizeToTray: (enabled) => ipcRenderer.invoke(ipcChannels.setMinimizeToTray, enabled),
   saveMcpServer: (input) => ipcRenderer.invoke(ipcChannels.saveMcpServer, input),
   deleteMcpServer: (serverId) => ipcRenderer.invoke(ipcChannels.deleteMcpServer, serverId),
   saveLspProfile: (input) => ipcRenderer.invoke(ipcChannels.saveLspProfile, input),
@@ -95,6 +96,12 @@ const api: ElectronApi = {
     ipcRenderer.on(ipcChannels.sessionEvent, handler);
     return () => ipcRenderer.off(ipcChannels.sessionEvent, handler);
   },
+  onTrayCreateScratchpad: (listener) => {
+    const handler = () => listener();
+
+    ipcRenderer.on(ipcChannels.trayCreateScratchpad, handler);
+    return () => ipcRenderer.off(ipcChannels.trayCreateScratchpad, handler);
+  },
 };
 
 contextBridge.exposeInMainWorld('aryxApi', api);