iris, rosa: nginx server alias for old names

This is a partial revert of 78c90687d8 I
was too eager in removing references to the radicle.garden domain. The
intention in that commit was to remove the old names from Radicle
aliases, but I mistakenly went too far and also removed these names
from the nginx configuration. Bring them back.

os/host/iris/radicle.nix

@@ -16,7 +16,10 @@
     options = ["discard=async" "noatime" "compress=zstd"];
   };
 
-  services.radicle.settings.node.externalAddresses = lib.mkAfter [
-    "irisradizskwweumpydlj4oammoshkxxjur3ztcmo7cou5emc6s5lfid.onion:8776"
-  ];
+  services.radicle = {
+    httpd.nginx.serverAliases = ["seed.radicle.garden"];
+    settings.node.externalAddresses = lib.mkAfter [
+      "irisradizskwweumpydlj4oammoshkxxjur3ztcmo7cou5emc6s5lfid.onion:8776"
+    ];
+  };
 }

os/host/rosa/radicle.nix

@@ -16,7 +16,10 @@
     options = ["discard=async" "noatime" "compress=zstd"];
   };
 
-  services.radicle.settings.node.externalAddresses = lib.mkAfter [
-    "rosarad5bxgdlgjnzzjygnsxrwxmoaj4vn7xinlstwglxvyt64jlnhyd.onion:8776"
-  ];
+  services.radicle = {
+    httpd.nginx.serverAliases = ["ash.radicle.garden"];
+    settings.node.externalAddresses = lib.mkAfter [
+      "rosarad5bxgdlgjnzzjygnsxrwxmoaj4vn7xinlstwglxvyt64jlnhyd.onion:8776"
+    ];
+  };
 }