v1.0.4

Single-instance guard + macOS Dock icon fixes

- Single-instance guard: dock/taskbar icon now raises the existing window
  instead of launching a second copy of the app.
- macOS Dock icon hides while the client window is minimized to the tray,
  and correctly reopens the window when reactivated via a pinned Dock icon.
- Fixed the tray/menu-bar icon opening both its menu and the window at
  once on macOS; now just shows the menu, matching native convention.