refactor(deploy): move deployment config into '<host>/meta.nix'

hosts/hecuba/meta.nix

@@ -1,5 +1,9 @@
 {
   system = "x86_64-linux";
-  deployment.tags = [ "cloud" ];
+  deployment = {
+    tags = [ "cloud" ];
+    targetHost = "server.hektormisplon.xyz";
+    targetUser = "username";
+  };
   role = "server";
 }