add main menu and scene manager

core/main_menu/main_menu.tscn

@@ -0,0 +1,62 @@
+[gd_scene format=3 uid="uid://btcpge7cj2041"]
+
+[ext_resource type="Script" uid="uid://csqxuftsnv1br" path="res://core/main_menu/main_menu.gd" id="1_g1whv"]
+[ext_resource type="PackedScene" uid="uid://cxf8s80ivwj1p" path="res://core/game_menu/option_menu.tscn" id="1_uvy4f"]
+[ext_resource type="Texture2D" uid="uid://b1wg4lif82dxp" path="res://core/main_menu/assets/photo_2025-08-27_17-35-14.jpg" id="2_mloc8"]
+[ext_resource type="PackedScene" uid="uid://caqf471x0kttc" path="res://core/game_menu/settings_menu.tscn" id="3_26agx"]
+
+[node name="MainMenu" type="Control" unique_id=889720172]
+layout_mode = 3
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+grow_horizontal = 2
+grow_vertical = 2
+script = ExtResource("1_g1whv")
+
+[node name="TextureRect" type="TextureRect" parent="." unique_id=11805511]
+layout_mode = 1
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+grow_horizontal = 2
+grow_vertical = 2
+texture = ExtResource("2_mloc8")
+
+[node name="OptionMenu" parent="." unique_id=1055457221 instance=ExtResource("1_uvy4f")]
+layout_mode = 1
+anchors_preset = 8
+anchor_left = 0.5
+anchor_top = 0.5
+anchor_right = 0.5
+anchor_bottom = 0.5
+offset_left = 492.0
+offset_top = 274.0
+offset_right = 492.0
+offset_bottom = 274.0
+
+[node name="VBoxContainer" parent="OptionMenu" index="0" unique_id=508055524]
+anchor_top = 0.3037037
+anchor_bottom = 0.6962963
+offset_top = 6.0
+offset_bottom = -6.0
+
+[node name="ResumeButton" parent="OptionMenu/VBoxContainer" index="1" unique_id=635721927]
+visible = false
+
+[node name="SaveButton" parent="OptionMenu/VBoxContainer" index="3" unique_id=1161034414]
+visible = false
+
+[node name="SettingsMenu" parent="." unique_id=1639777294 instance=ExtResource("3_26agx")]
+unique_name_in_owner = true
+visible = false
+layout_mode = 1
+offset_left = 639.0
+offset_top = 566.0
+offset_right = 639.0
+offset_bottom = 566.0
+
+[connection signal="on_button_pressed" from="OptionMenu/VBoxContainer/PlayButton" to="." method="_on_play_button_on_button_pressed"]
+[connection signal="on_button_pressed" from="OptionMenu/VBoxContainer/SettingsButton" to="." method="_on_settings_button_on_button_pressed"]
+
+[editable path="OptionMenu"]