refactor(flake): split host guest and module assembly

lib/network.nix

@@ -0,0 +1,12 @@
+{ lib }:
+{
+  bridgeName = id: "br-vlan${toString id}";
+
+  deriveMac =
+    name:
+    let
+      hash = builtins.hashString "sha256" name;
+      octet = i: builtins.substring (i * 2) 2 hash;
+    in
+    lib.concatStringsSep ":" ([ "02" ] ++ map octet [ 0 1 2 3 4 ]);
+}