feat: add Spectator Mode

include/Cubed/gameplay/game_mode.hpp

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <stdexcept>
+#include <string>
+enum class GameMode {
+    CREATIVE,
+    SPECTATOR
+};
+
+inline std::string to_str(GameMode mode) {
+    using enum GameMode;
+    switch (mode) {
+        case CREATIVE:
+            return {"Creative"};
+        case SPECTATOR:
+            return {"Spective"};
+    }
+    throw std::invalid_argument{"GameMode is invaild"};
+}