Fix building many things in nix.

Nix 2.30.0 (2025-07-07) changed the build directory from /tmp to /nix/var/nix/builds which broke a number of builds because my ZFS datasets were utf8only. This adds a role to mount tmpfs to /nix/var/nix/builds to restore the old behavior.

nix/configuration/hosts/odo/default.nix

@@ -68,6 +68,7 @@
     me.base.enable = true;
     me.bluetooth.enable = true;
     me.boot.enable = true;
+    me.build_in_ram.enable = true;
     me.chromecast.enable = true;
     me.chromium.enable = true;
     me.d2.enable = true;

nix/configuration/hosts/quark/default.nix

@@ -62,6 +62,7 @@
     me.base.enable = true;
     me.bluetooth.enable = true;
     me.boot.enable = true;
+    me.build_in_ram.enable = true;
     me.chromecast.enable = true;
     me.chromium.enable = true;
     me.d2.enable = true;

nix/configuration/hosts/recovery/default.nix

@@ -47,11 +47,16 @@
     # Enable TRIM
     # services.fstrim.enable = lib.mkDefault true;
 
+    me.build_in_ram.enable = true;
+    me.doas.enable = true;
+    me.network.enable = true;
+    me.nvme.enable = true;
     me.recovery.enable = true;
     me.ssh.enable = true;
     me.sshd.enable = true;
     me.user.enable = true;
     me.zfs.enable = true;
     me.zrepl.enable = true;
+    me.zsh.enable = true;
   };
 }