Add a gradient interpolation space attribute with sRGB Gamma (existing) and sRGB Linear (new) (#4412)

* Build dropdown menu entries from choice type metadata

* Add a gradient interpolation color space attribute, blending stops in linear light by default

* Add a Space interpolation dropdown to the color picker popover

* Stamp legacy gradient ramps with their implicit gamma interpolation during deserialization

* Resolve color-interpolation from SVG style blocks and fix cascade order among repeated declarations

node-graph/nodes/graphic/src/graphic.rs

@@ -9,7 +9,7 @@ use rand::SeedableRng;
 use rand::seq::SliceRandom;
 use raster_types::{CPU, GPU, Raster};
 use std::cmp::Ordering;
-use vector_types::gradient::{GradientForm, GradientSpread};
+use vector_types::gradient::{GradientForm, GradientInterpolation, GradientSpread};
 use vector_types::{Gradient, ReferencePoint};
 
 /// Returns the list with the item at the specified index removed.
@@ -747,6 +747,23 @@ fn read_attribute_gradient_spread(
 	result
 }
 
+/// Reads a named `GradientInterpolation` attribute from the input list, outputting each value as an element of a new `GradientInterpolation[]`.
+#[node_macro::node(category("Attributes: Read"))]
+fn read_attribute_gradient_interpolation(
+	_: impl Ctx,
+	content: ListDyn,
+	/// The attribute name (key) to read.
+	name: Item<String>,
+) -> List<GradientInterpolation> {
+	let name = name.into_element();
+	let mut result = List::with_capacity(content.len());
+	for index in 0..content.len() {
+		let Some(value) = content.attribute::<GradientInterpolation>(&name, index) else { continue };
+		result.push(Item::new_from_element(*value));
+	}
+	result
+}
+
 /// Reads a named `Gradient` attribute from the input list, outputting each value as an element of a new `Gradient[]`.
 #[node_macro::node(category("Attributes: Read"))]
 fn read_attribute_gradient_stops(