feat: Add a lot more features

- Add new system.rs module for system monitoring via D-Bus:
  - Battery status (UPower)
  - Media player controls and metadata (MPRIS)
  - WiFi/Bluetooth status (NetworkManager)
  - Keyboard layout tracking
- Add media key support (XF86 Play/Pause/Next/Prev)
- Add function keys F1-F3 for Suspend/Reboot/PowerOff
- Replace deprecated timer.rs with async system management
- Add GitHub Actions CI/CD workflows (CI + Release)
- Update dependencies and add optional networking feature

default.nix

@@ -10,7 +10,10 @@ pkgs.rustPlatform.buildRustPackage {
     cairo
     pam
     gdk-pixbuf
+    librsvg
+    pango
     libxkbcommon
+    dbus
   ];
 
   nativeBuildInputs = [