fix(chat): correct .well-known URLs

By default, conduit assumes your .well-known URLs are the same as your
base URL (for us auxolotl.org). Unfortunately, although we want our
accounts to be @foo:auxolotl.org, our server is actually at
matrix.auxolotl.org, which broke some clients such as commet

Correcting these .well-known URLs allows clients to connect again

modules/nixos/auxolotl/services/chat/default.nix

@@ -77,6 +77,10 @@ in {
         global = {
           server_name = cfg.domain;
           allow_registration = false;
+          well_known = {
+            server = "matrix.auxolotl.org:443";
+            client = "https://matrix.auxolotl.org";
+          };
         };
       };
     };