feat: add NixOS module for HackerGadgets AIO v2 board (uConsole CM5)

- New module: hardware.uconsole-cm5-aio-v2
  - GPIO rail control for GPS (27), LORA (16), SDR (7), USB (23)
  - Systemd oneshot service (aiov2-rails-boot) to apply states at boot
  - aiov2_ctl CLI tool packaged from GitHub source
  - GPS UART support (ttyAMA0, 9600 baud) with dialout group
  - Optional systemd user service for system tray GUI
- Wired into uconsole-cm5 NixOS config + SD image

All rails default OFF — activate on demand with:
  aiov2_ctl <GPS|LORA|SDR|USB> on

flake.nix

@@ -120,6 +120,7 @@
               };
             in { nix.package = lix-cross.lix; })
             agenix.nixosModules.default
+            ./modules/nixos/hardware/uconsole-cm5-aio-v2.nix
             ./hosts/uconsole-cm5/configuration.nix
             ./hosts/uconsole-cm5/hardware-configuration.nix
           ];
@@ -147,6 +148,7 @@
             nixos-raspberrypi.nixosModules.sd-image
             nixos-uconsole.nixosModules.uconsole-cm5
             agenix.nixosModules.default
+            ./modules/nixos/hardware/uconsole-cm5-aio-v2.nix
             ./hosts/uconsole-cm5/configuration.nix
           ];
         }).config.system.build.sdImage;