feat: create shared extraHosts module with Tailscale IPs

- Create modules/network/extraHosts.nix with Tailscale IP mappings
- Replace hardcoded networking.extraHosts in all machine configs
- Add extraHosts module import to all machines
- Enable Tailscale service by default in the module
- Use Tailscale mesh network IPs for reliable connectivity

machines/congenital-optimist/configuration.nix

@@ -12,6 +12,9 @@
     # Security modules
     ../../modules/security/ssh-keys.nix
     
+    # Network modules
+    ../../modules/network/extraHosts.nix
+    
     # Hardware modules
     ../../modules/hardware/amd-workstation.nix
     
@@ -45,8 +48,7 @@
         path = "/boot";
       }
     ];
-  };
-# ZFS services for this machine
+  };  # ZFS services for this machine
   services.zfs = {
     autoScrub.enable = true;
     trim.enable = true;

machines/grey-area/configuration.nix

@@ -8,6 +8,7 @@
     # Shared modules
     ../../modules/common/base.nix
     ../../modules/network/common.nix
+    ../../modules/network/extraHosts.nix
     ../../modules/virtualization/podman.nix
     ../../modules/virtualization/libvirt.nix
     ../../modules/virtualization/incus.nix
@@ -64,11 +65,6 @@
   # Networking
   networking.hostName = "grey-area"; 
   networking.networkmanager.enable = true;
-  
-  # Add hostname resolution for sleeper-service NFS server
-  networking.extraHosts = ''
-    10.0.0.8 sleeper-service
-  '';  
 
   # Set your time zone.
   time.timeZone = "Europe/Oslo";

machines/reverse-proxy/configuration.nix

@@ -4,6 +4,7 @@
   imports = [ 
     ./gandicloud.nix
     ../../modules/common/base.nix
+    ../../modules/network/extraHosts.nix
     ../../modules/users/sma.nix
     ../../modules/security/ssh-keys.nix
   ];

machines/sleeper-service/configuration.nix

@@ -5,6 +5,7 @@
     ../../modules/security/ssh-keys.nix
     # Network configuration
     ./network-sleeper-service.nix
+    ../../modules/network/extraHosts.nix
     # Services
     ./nfs.nix
     ./services/transmission.nix