add player package with key client-side player functionality, update protocol codecs, and refactor metadata definitions and slot usage

pkg/bot/event.go

@@ -0,0 +1,20 @@
+package bot
+
+type EventHandler interface {
+	PublishEvent(event string, data any) error
+	SubscribeEvent(event string, handler func(data any) error)
+}
+
+type Event interface {
+	EventID() string
+}
+
+func PublishEvent(client Client, event Event) error {
+	return client.EventHandler().PublishEvent(event.EventID(), event)
+}
+
+func SubscribeEvent(client Client, event string, handler func(event Event) error) {
+	client.EventHandler().SubscribeEvent(event, func(data any) error {
+		return handler(data.(Event))
+	})
+}