fix(deploy): assign unique WireGuard IPs per machine

Move WireGuard IP from shared configuration.nix to per-machine
hardware configs. douro = 10.0.0.4, batm3 = 10.0.0.5.

Previously both machines shared 10.0.0.4 which caused routing
conflicts on the VPS.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

deploy/nixos/configuration.nix

@@ -22,8 +22,8 @@
     };
 
     # WireGuard VPN tunnel to VPS for remote SSH access
+    # IP address set per-machine in hardware/*.nix via networking.wireguard.interfaces.wg0.ips
     wireguard.interfaces.wg0 = {
-      ips = [ "10.0.0.4/24" ];
       listenPort = 51820;
       privateKeyFile = "/var/lib/wireguard/wg0.key";
 

deploy/nixos/hardware/batm3.nix

@@ -136,4 +136,7 @@
       ExecStart = "${pkgs.xorg.xinput}/bin/xinput set-prop 'eGalax Inc. USB TouchController' 'Coordinate Transformation Matrix' 0 -1.268 1.147 -1.224 0 1.118 0 0 1";
     };
   };
+
+  # WireGuard VPN address
+  networking.wireguard.interfaces.wg0.ips = [ "10.0.0.5/24" ];
 }

deploy/nixos/hardware/douro.nix

@@ -80,6 +80,9 @@
     hybrid-sleep.enable = false;
   };
 
+  # WireGuard VPN address
+  networking.wireguard.interfaces.wg0.ips = [ "10.0.0.4/24" ];
+
   # Serial port access for bill validator/dispenser
   services.udev.extraRules = lib.mkAfter ''
     KERNEL=="ttyS[0-9]*", MODE="0666"