chore(event): move CObserver from ui to event

src/event/CObserver.hpp

@@ -0,0 +1,8 @@
+#ifndef EVENT_C_OBSERVER_HPP
+#define EVENT_C_OBSERVER_HPP
+
+class CObserver {
+    // TODO
+};
+
+#endif

src/ui/CObserver.hpp

@@ -1,8 +0,0 @@
-#ifndef UI_C_OBSERVER_HPP
-#define UI_C_OBSERVER_HPP
-
-class CObserver {
-    // TODO
-};
-
-#endif