feat: Improve the initial setup experience

- Issue a single-use token for initial account creation
- Disable registration through other methods until the first account is made
- Print helpful instructions to the console on the first run
- Improve the welcome message sent in the admin room on first run

src/service/admin/mod.rs

@@ -137,7 +137,6 @@ impl crate::Service for Service {
 		let mut signals = self.services.server.signal.subscribe();
 		let receiver = self.channel.1.clone();
 
-		self.startup_execute().await?;
 		self.console_auto_start().await;
 
 		loop {