feat: add upgrade popup prototype

include/render/WorldRenderer.h

@@ -26,6 +26,7 @@ private:
     glm::vec2 m_CamPos;
     glm::vec2 m_CursorPos;
     glm::vec2 m_HoldCursorPos;
+    glm::vec2 m_LastClicked;
     float m_Zoom;
     float m_CamSensibility = 1;
     bool m_PopupOpened = false;
@@ -52,9 +53,9 @@ private:
     void renderTowers() const;
     void renderMobs() const;
     void renderTileSelect() const;
-    void renderPopups() const;
-    void renderTowerPlacePopup() const;
-    void renderTowerUpgradePopup() const;
+    void renderPopups();
+    void renderTowerPlacePopup();
+    void renderTowerUpgradePopup();
     void renderMobTooltip() const;
     void detectClick();
     glm::vec2 getCursorWorldPos() const;