t2-iso-minimal, t2-iso-gnome: use binary cache and keep common settings in common.nix

flake.nix

@@ -23,5 +23,5 @@
         inherit nixos-hardware;
       };
     }).config.system.build.isoImage; 
-  }) (builtins.filter (x: x != null) (lib.attrsets.mapAttrsToList (key: value: if value == "regular" then ./nix/${key} else null) (builtins.readDir ./nix)));
+  }) (builtins.filter (x: x != null) (lib.attrsets.mapAttrsToList (key: value: if value == "regular" && lib.strings.hasInfix "iso" key then ./nix/${key} else null) (builtins.readDir ./nix)));
 }

nix/common.nix

@@ -0,0 +1,12 @@
+{ ... }:
+
+{
+  nix = {
+    binaryCaches = [
+      "https://t2linux.cachix.org"
+    ];
+    binaryCachePublicKeys = [
+      "t2linux.cachix.org-1:P733c5Gt1qTcxsm+Bae0renWnT8OLs0u9+yfaK2Bejw="
+    ];
+  };
+}

nix/t2-iso-gnome.nix

@@ -5,6 +5,7 @@
     "${modulesPath}/installer/cd-dvd/installation-cd-graphical-gnome.nix"
     "${modulesPath}/installer/cd-dvd/channel.nix"
     nixos-hardware.nixosModules.apple-t2
+    ./common.nix
   ];
 
   # Audio works better with PipeWire

nix/t2-iso-minimal.nix

@@ -5,6 +5,7 @@
     "${modulesPath}/installer/cd-dvd/installation-cd-minimal.nix"
     "${modulesPath}/installer/cd-dvd/channel.nix"
     nixos-hardware.nixosModules.apple-t2
+    ./common.nix
   ];
 
   # ZFS is broken and prevents building without this