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

pkg/game/world/event.go

@@ -0,0 +1,19 @@
+package world
+
+import "git.konjactw.dev/patyhank/minego/pkg/bot"
+
+type EntityRemoveEvent struct {
+	Entity bot.Entity
+}
+
+func (e EntityRemoveEvent) EventID() string {
+	return "world:entity_remove"
+}
+
+type EntityAddEvent struct {
+	EntityID int32
+}
+
+func (e EntityAddEvent) EventID() string {
+	return "world:entity_add"
+}