Refactor the 'Fill' and 'Stroke' nodes to set "fill" and "stroke" attributes for paints (#4257)

* Allow using any graphics type for fill

* Adapt gradient/fill property panels and tools to handle List<T>

* Make the initial gradient transform covers the target's bounding box

* Introduce AnyGraphicListDyn to avoid combinatorial explosion

* Allow using any graphics type for stroke paint

* Add FIll node migration

* Add `for_each_vector_list_mut` instead of `set_paint_attribute`

* Adapt paint flow to read and write attributes instead of legacy Fill/Stroke.color

* Fix responsibilities of paint related node input setters

* Fix Morph by storing List<Graphic> for attributes rather than the concrete types

Store fill/stroke paints as List<Graphic> so Color/Gradient transitions
do not hit set_attribute_value_dyn's type-mismatch fallback to default paint.

* Preserve paint attributes in vector editing ops

* Enhance the clarity between direct and chained fill gradients

* Update demo arts

* Consolidate Fill node gradient appearance inputs

* Fix after the cubic review

* Revert "Consolidate Fill node gradient appearance inputs"

This reverts commit 9622feb20196e2c4da99e98ca95dcc2e34c2c98e.

* Replace AnyGraphicListDyn with generic paint connectors on the Fill and Stroke nodes

* Canonicalize paint attribute storage to List<Graphic> with a single write helper

* Fix Solidify Stroke missing fills stored in the legacy style

* Fix Solidify Stroke producing invisible strokes for legacy-only stroke colors

* Fix the initial gradient transform ignoring the bounding box's vertical extent

* Step paint at the morph midpoint instead of dropping it for unmixable pairings

* Remove migration-stage comments

* Clarify the initial gradient transform helper's doc and name

* Correct the bake_paint_transforms doc and prune dead tolerance arms

* Delete the unused Gradient::lerp

* Fix a comment typo

* Thread network paths through the legacy gradient bake so nested fills migrate

* Restore the legacy fill fallback in Expand Fill and Stroke

* Read gradient stops from the node's own input in the Fill properties panel

* Use the transform input constant instead of a hardcoded index

* Remove the unreachable wired color fallback in the Fill properties solid branch

* Narrow the fill overlay redraw check to actual fill inputs

* Coalesce the fill setter's graph runs into a single dispatch

* Position the Gradient Value node inserted for gradient stops

* Bake backup gradient placement during migration

* Persist pending gradient bakes so unfinished migrations retry on reopen

* Migrate the backup gradient's type and spread method

* Harden the gradient-migration pass against document switches and stale bakes

* Keep the Fill properties UI for layerless and nested Fill nodes

* Leave a wired gradient transform input connected instead of overwriting it

* Refuse to start a gradient chain ahead of existing layer content

* Decode a Fill node's gradient through one shared reader

* Nudge a degenerate bounding box so the Fill gradient transform stays invertible

* Broadcast Fill and Stroke paint with a single attribute-column pass

* Fix Morph stepping the target's stroke in near the source instead of the target

* Tidy conventions: clippy get_first, comment periods, sentence-case test messages

* Reattach the gradient orientation doc to its function

* Re-save demo artwork

---------

Co-authored-by: Keavon Chambers <keavon@keavon.com>

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

@@ -9,7 +9,7 @@ use vector_types::GradientStops;
 
 /// Constructs a single-element `Artboard[]` with the given content and metadata stored as row attributes.
 #[node_macro::node(category(""))]
-pub async fn create_artboard<T: IntoGraphicList + 'n>(
+pub async fn create_artboard<T: IntoGraphicList>(
 	ctx: impl ExtractAll + CloneVarArgs + Ctx,
 	/// Graphics to include within the artboard.
 	#[implementations(

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

@@ -565,7 +565,7 @@ pub async fn wrap_graphic<T: Into<Graphic> + 'n>(
 /// Converts a list of graphical content into a `Graphic[]` by placing it into an element of a new wrapper `Graphic[]`.
 /// If it is already a `Graphic[]`, it is not wrapped again. Use the 'Wrap Graphic' node if wrapping is always desired.
 #[node_macro::node(category("General"))]
-pub async fn to_graphic<T: IntoGraphicList + 'n>(
+pub async fn to_graphic<T: IntoGraphicList>(
 	_: impl Ctx,
 	#[implementations(
 		List<Graphic>,
@@ -620,7 +620,7 @@ pub async fn flatten_graphic(_: impl Ctx, content: List<Graphic>, fully_flatten:
 
 /// Converts a `Graphic[]` into a `Vector[]` by deeply flattening any vector content it contains, and discarding any non-vector content.
 #[node_macro::node(category("Vector"))]
-pub async fn flatten_vector<T: IntoGraphicList + 'n + Send + Clone>(_: impl Ctx, #[implementations(List<Graphic>, List<Vector>)] content: T) -> List<Vector> {
+pub async fn flatten_vector<T: IntoGraphicList>(_: impl Ctx, #[implementations(List<Graphic>, List<Vector>)] content: T) -> List<Vector> {
 	let graphic_list = content.into_graphic_list();
 	let mut output: List<Vector> = graphic_list.clone().into_flattened_list();
 
@@ -653,25 +653,25 @@ pub async fn flatten_vector<T: IntoGraphicList + 'n + Send + Clone>(_: impl Ctx,
 
 /// Converts a `Graphic[]` into a `Raster[]` by deeply flattening any raster content it contains, and discarding any non-raster content.
 #[node_macro::node(category("Raster"))]
-pub async fn flatten_raster<T: IntoGraphicList + 'n + Send + Clone>(_: impl Ctx, #[implementations(List<Graphic>, List<Raster<CPU>>)] content: T) -> List<Raster<CPU>> {
+pub async fn flatten_raster<T: IntoGraphicList>(_: impl Ctx, #[implementations(List<Graphic>, List<Raster<CPU>>)] content: T) -> List<Raster<CPU>> {
 	content.into_flattened_list()
 }
 
 /// Converts a `Graphic[]` into a `Color[]` by deeply flattening any color content it contains, and discarding any non-color content.
 #[node_macro::node(category("General"))]
-pub async fn flatten_color<T: IntoGraphicList + 'n + Send + Clone>(_: impl Ctx, #[implementations(List<Graphic>, List<Color>)] content: T) -> List<Color> {
+pub async fn flatten_color<T: IntoGraphicList>(_: impl Ctx, #[implementations(List<Graphic>, List<Color>)] content: T) -> List<Color> {
 	content.into_flattened_list()
 }
 
 /// Converts a `Graphic[]` into a `GradientStops[]` by deeply flattening any gradient content it contains, and discarding any non-gradient content.
 #[node_macro::node(category("General"))]
-pub async fn flatten_gradient<T: IntoGraphicList + 'n + Send + Clone>(_: impl Ctx, #[implementations(List<Graphic>, List<GradientStops>)] content: T) -> List<GradientStops> {
+pub async fn flatten_gradient<T: IntoGraphicList>(_: impl Ctx, #[implementations(List<Graphic>, List<GradientStops>)] content: T) -> List<GradientStops> {
 	content.into_flattened_list()
 }
 
 /// Constructs a gradient from a `Color[]`, where the colors are evenly distributed as gradient stops across the range from 0 to 1.
 #[node_macro::node(category("Color"))]
-fn colors_to_gradient<T: IntoGraphicList + 'n + Send + Clone>(_: impl Ctx, #[implementations(List<Graphic>, List<Color>)] colors: T) -> List<GradientStops> {
+fn colors_to_gradient<T: IntoGraphicList>(_: impl Ctx, #[implementations(List<Graphic>, List<Color>)] colors: T) -> List<GradientStops> {
 	let colors = colors.into_flattened_list::<Color>();
 	let total_colors = colors.len();