flora-6: move ISO images to /data

There is a second, bigger disk attached to flora-6, let's use it

hosts/flora-6/caddy.nix

@@ -10,6 +10,10 @@
     config.services.caddy.configFile
   ];
 
+  systemd.tmpfiles.rules = [
+    "d '/data/srv/www/os/download/' 0750 hakkonaut hakkonaut - -"
+  ];
+
   services.caddy = {
     enable = lib.mkForce true;
     group = "hakkonaut";
@@ -23,7 +27,7 @@
         extraConfig = ''
           # PubSolarOS images
           handle /os/download/* {
-            root * /srv/www
+            root * /data/srv/www
             file_server /os/download/* browse
           }
           # serve base domain pub.solar for mastodon.pub.solar