feat(startscreen): add button initialization

src/button.py

@@ -10,7 +10,14 @@ class Button:
         self.color = color
         self.hover = hover
 
-        # todo
+        # create rectangle for button
+        self.rect = pygame.Rect(self.pos_x, self.pos_y, self.width, self.height)
+
+        # set font for button text
+        self.font = pygame.font.SysFont("Arial", 30)
+
+        # temp var to stor click event - so it will be executed just once
+        self.clicked = False
 
     def draw(self, screen):
         action = False