fix(ircserver): VERSION/ADMIN/TIME use serverSfx fallback

WIP: c.cfg.ServerName defaults to "", so the three new wire handlers
emitted an empty server-name parameter under the shipped default config.
c.serverSfx already carries the same "neoirc" fallback the HTTP path
uses, and sendNumeric uses it for the prefix. Empty-ServerName test
follows.

internal/ircserver/commands.go

@@ -1350,14 +1350,14 @@ func (c *Conn) handleUserhost(
 func (c *Conn) handleVersion() {
 	c.sendNumeric(
 		irc.RplVersion,
-		c.svc.ServerVersion()+".", c.cfg.ServerName,
+		c.svc.ServerVersion()+".", c.serverSfx,
 		"",
 	)
 }
 
 // handleAdmin replies with server admin info.
 func (c *Conn) handleAdmin() {
-	srvName := c.cfg.ServerName
+	srvName := c.serverSfx
 
 	c.sendNumeric(
 		irc.RplAdminMe,
@@ -1394,7 +1394,7 @@ func (c *Conn) handleInfo() {
 
 // handleTime replies with the server's current time.
 func (c *Conn) handleTime() {
-	srvName := c.cfg.ServerName
+	srvName := c.serverSfx
 
 	c.sendNumeric(
 		irc.RplTime,