v1.3.0 - waycentral

Add updates, volume, network, layout, music and systray modules

- Updates (-u): libalpm checkupdates-style count per enabled repo + AUR
  via the RPC, every 30 min and after each pacman transaction
- Volume (-V OUT|IN): libpulse, event driven, detects speaker/headphones/
  headset/mic; up/down/set/mute/toggle/next-device controls
- Network (-n): NetworkManager over sd-bus, sysfs fallback
- Layout (-l): Hyprland tiledLayout over the IPC socket, event driven
- Music (-m): MPRIS over sd-bus, preferred player, controls, launches
  the player binary when it is not running
- Systray: waybar CFFI module (GTK3) with symbolic theme icons, dbusmenu
  menus and its own StatusNotifierWatcher
- Date: new calendar (week numbers, neighbouring days, today highlight),
  month navigation with -d next/prev/today
- CLI: exit when Waybar closes stdout instead of lingering
- Build releases in an Arch container; bump version to 1.3.0

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>