Add layer scaling, greyscale effect, and context menu

- Fix onnxruntime version (1.15.1) to avoid executable stack issue
- Add Layer Scale module (Layer > Scale Layer or 'S' button)
- Add Greyscale effect with multiple methods (luminosity, average, etc.)
- Add right-click context menu on layers with common operations
- Add Scale button to layers panel toolbar

frontend/src/js/config-menu.js

@@ -326,6 +326,11 @@ const menuDefinition = [
 				name: 'Convert to Raster',
 				target: 'layer/raster.raster'
 			},
+			{
+				name: 'Scale Layer',
+				ellipsis: true,
+				target: 'layer/scale.scale'
+			},
 			{
 				divider: true
 			},
@@ -480,6 +485,11 @@ const menuDefinition = [
 				ellipsis: true,
 				target: 'effects/black_and_white.black_and_white'
 			},
+			{
+				name: 'Greyscale',
+				ellipsis: true,
+				target: 'effects/greyscale.greyscale'
+			},
 			{
 				name: 'Borders',
 				ellipsis: true,