Rework avatars.

Now we have a concept of an avatar at the server, realm, and scene level
and we have the groundwork for a realm store. New uesrs no longer props,
they get a default avatar. New system supports gender
{male,female,neutral} and {child,adult}.

apps/chattyness-app/src/main.rs

@@ -178,6 +178,7 @@ mod server {
             leptos_options: leptos_options.clone(),
             ws_state: ws_state.clone(),
             ws_config: config.websocket.clone(),
+            signup_config: config.signup.clone(),
         };
         let admin_api_state = chattyness_admin_ui::AdminAppState {
             pool: pool.clone(),