Add opacity slider with shader-based rendering that preserves clip mask behavior

- Added opacity slider (0-100%) in sprite options with 'affect children' checkbox
- Implemented hierarchical opacity that affects entire sprite hierarchy when enabled
- Created shader-based opacity system that doesn't interfere with clip mask functionality
- Clip masks now work with original image pixels regardless of opacity settings
- Removed shadow effects from selected sprites to prevent visual conflicts
- Updated save/load system to persist opacity properties with backward compatibility

Fixes clipping behavior issues where opacity changes previously affected clip mask detection

ui_scenes/spriteEditMenu/sprite_viewer.tscn

@@ -29,7 +29,7 @@
 [ext_resource type="Texture2D" uid="uid://gflmeocxfnrq" path="res://ui_scenes/settings/deleteHotkey.png" id="27_fgu6g"]
 
 [sub_resource type="RectangleShape2D" id="RectangleShape2D_21kva"]
-size = Vector2(245, 1341)
+size = Vector2(245, 1455)
 
 [sub_resource type="ShaderMaterial" id="ShaderMaterial_hxmah"]
 shader = ExtResource("3_ky0lu")
@@ -14285,11 +14285,12 @@ script = ExtResource("1_hp0e3")
 z_index = -2
 
 [node name="CollisionShape2D" type="CollisionShape2D" parent="Area2D"]
-position = Vector2(122.5, 670.5)
+position = Vector2(122.5, 727.5)
 shape = SubResource("RectangleShape2D_21kva")
 
 [node name="Border" type="Sprite2D" parent="."]
-scale = Vector2(1, 1.16)
+position = Vector2(0, 2.22901)
+scale = Vector2(1, 1.37547)
 texture = ExtResource("1_b54o8")
 centered = false
 offset = Vector2(-9, -10.3448)
@@ -14349,13 +14350,13 @@ transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 3.362)
 fov = 36.5
 
 [node name="Position" type="Node2D" parent="."]
-position = Vector2(0, 10)
+position = Vector2(0, 20)
 
 [node name="fileTitle" type="Label" parent="Position"]
 offset_left = 10.0
-offset_top = 134.0
+offset_top = 127.0
 offset_right = 236.0
-offset_bottom = 154.0
+offset_bottom = 147.0
 text = "user://greenThing/head1.png"
 label_settings = SubResource("LabelSettings_6favr")
 
@@ -14381,7 +14382,7 @@ offset_bottom = 227.0
 text = "layer : 0"
 
 [node name="Buttons" type="Node2D" parent="."]
-position = Vector2(0, 27)
+position = Vector2(0, 141)
 
 [node name="Speaking" type="Sprite2D" parent="Buttons"]
 position = Vector2(42, 523)
@@ -14468,7 +14469,7 @@ scrollable = false
 
 [node name="WobbleControl" type="Node2D" parent="."]
 z_index = 1
-position = Vector2(-3, 378)
+position = Vector2(-3, 486)
 
 [node name="animationBox" type="Sprite2D" parent="WobbleControl"]
 position = Vector2(125, 384.5)
@@ -14612,7 +14613,7 @@ scrollable = false
 
 [node name="RotationalLimits" type="Node2D" parent="."]
 z_index = -1
-position = Vector2(0, 325)
+position = Vector2(0, 435)
 
 [node name="RotBack" type="Sprite2D" parent="RotationalLimits"]
 clip_children = 2
@@ -14725,8 +14726,43 @@ offset_bottom = 1068.0
 theme = SubResource("Theme_mrbyn")
 scrollable = false
 
+[node name="Opacity" type="Node2D" parent="."]
+position = Vector2(-2, -611)
+
+[node name="opacityLabel" type="Label" parent="Opacity"]
+offset_left = 11.0
+offset_top = 1090.0
+offset_right = 159.0
+offset_bottom = 1116.0
+text = "opacity: 100%"
+
+[node name="opacitySlider" type="HSlider" parent="Opacity"]
+offset_left = 10.0
+offset_top = 1111.0
+offset_right = 233.0
+offset_bottom = 1131.0
+theme = SubResource("Theme_mrbyn")
+max_value = 1.0
+step = 0.01
+value = 1.0
+scrollable = false
+
+[node name="affectChildrenLabel" type="Label" parent="Opacity"]
+offset_left = 11.0
+offset_top = 1140.0
+offset_right = 159.0
+offset_bottom = 1166.0
+text = "affect children:"
+
+[node name="affectChildrenCheck" type="CheckBox" parent="Opacity"]
+offset_left = 140.0
+offset_top = 1140.0
+offset_right = 200.0
+offset_bottom = 1166.0
+theme = SubResource("Theme_mrbyn")
+
 [node name="Layers" type="Node2D" parent="."]
-position = Vector2(0, 327)
+position = Vector2(0, 443)
 
 [node name="Layer1" type="Sprite2D" parent="Layers"]
 position = Vector2(23, 878)
@@ -14863,7 +14899,7 @@ position = Vector2(23, 878)
 texture = ExtResource("20_px0dt")
 
 [node name="VisToggle" type="Node2D" parent="."]
-position = Vector2(11, 1289)
+position = Vector2(11, 1404)
 
 [node name="setToggle" type="Button" parent="VisToggle"]
 custom_minimum_size = Vector2(0, 37.125)
@@ -14929,6 +14965,8 @@ centered = false
 [connection signal="value_changed" from="RotationalLimits/rotLimitMax" to="." method="_on_rot_limit_max_value_changed"]
 [connection signal="value_changed" from="Animation/animFrames" to="." method="_on_anim_frames_value_changed"]
 [connection signal="value_changed" from="Animation/animSpeed" to="." method="_on_anim_speed_value_changed"]
+[connection signal="value_changed" from="Opacity/opacitySlider" to="." method="_on_opacity_slider_value_changed"]
+[connection signal="toggled" from="Opacity/affectChildrenCheck" to="." method="_on_affect_children_check_toggled"]
 [connection signal="pressed" from="Layers/Layer1/layerButton1" to="." method="_on_layer_button_1_pressed"]
 [connection signal="pressed" from="Layers/Layer2/layerButton2" to="." method="_on_layer_button_2_pressed"]
 [connection signal="pressed" from="Layers/Layer3/layerButton3" to="." method="_on_layer_button_3_pressed"]