Effects: Effect › Rasterize draws an object as pixels while its paths stay editable

The Effect menu had no Rasterize. Object › Rasterize replaces the
object with an image, so its paths can no longer be edited.

Effect › Rasterize… (`rasterize`) is a live effect with Object ›
Rasterize's options: color model, resolution (the document's raster
effects resolution by default), white or transparent background,
anti-aliasing, Create Clipping Mask and Add Around Object. The canvas
draws the object as square pixels over its bounds, and its paths, type
and other art stay as they are. The effects above it in the stack,
shadows included, are part of its image, and shadows below it are cast
by the image. When Rasterize is an object's only raster effect, Expand
Appearance and PDF and SVG export give the image Object › Rasterize
gives with the same options.

Object › Rasterize now measures the art as drawn, with its geometry
effects, brush art and raster effects, so a Transform effect that moves
the art no longer leaves the image empty. Its Create Clipping Mask
clips the image to the art as drawn. The canvas no longer panics
drawing a pixel effect such as Gaussian Blur on an object about 65,500
screen pixels wide: the raster of such an object is at most 32,768
pixels a side, and the object is drawn into it at a lower resolution.

Docs: docs/mcp.md, docs/effects-parity.md, docs/target-app-parity.md,
ROADMAP.

crates/engine/src/cmd/effectcmd.rs

@@ -59,7 +59,7 @@ pub fn specs() -> Vec<CommandSpec> {
             "Expand Appearance",
             ["Object"],
             None,
-            "{ids?|id?: [..], target?} turn each object's appearance into objects: every fill and stroke becomes an object of its own (strokes outlined, brushed strokes their brush art) grouped in paint order under the object's id and transparency, geometry effects are baked, raster effects become an embedded image (shadows and outer glows below the art; blur, feather and inner glow replace it), type with effects or fills of its own is outlined; Crop Marks become a group of the object and its marks; a group's or layer's own fills and strokes become objects among its members, which are expanded too. Hidden fills, strokes and effects are dropped. Enabled when a selected or targeted object's appearance isn't basic (`ids` then pick which objects) → {ids}",
+            "{ids?|id?: [..], target?} turn each object's appearance into objects: every fill and stroke becomes an object of its own (strokes outlined, brushed strokes their brush art) grouped in paint order under the object's id and transparency, geometry effects are baked, raster effects become an embedded image (shadows and outer glows below the art; blur, feather and inner glow replace it; an object whose only raster effect is its own Rasterize becomes the image object.rasterize makes with the effect's options), type with effects or fills of its own is outlined; Crop Marks become a group of the object and its marks; a group's or layer's own fills and strokes become objects among its members, which are expanded too. Hidden fills, strokes and effects are dropped. Enabled when a selected or targeted object's appearance isn't basic (`ids` then pick which objects) → {ids}",
             can_expand,
             expand_appearance
         ),
@@ -421,9 +421,10 @@ fn is_container(n: &Node) -> bool {
 }
 
 /// The raster effects of `n` (its own, its fills' and strokes') as an embedded image rendered at
-/// the document's raster effects resolution, with whether they all paint below it (shadows and
-/// outer glows: the image then holds just them). A group's or layer's image leaves out its
-/// members' raster effects, which are expanded with them. `None` when it has none.
+/// the document's raster effects resolution or a Rasterize effect's finer one, with whether they
+/// all paint below it (shadows and outer glows: the image then holds just them). A group's or
+/// layer's image leaves out its members' raster effects, which are expanded with them. `None`
+/// when it has none.
 fn raster_image(d: &mut Document, n: &Node) -> Option<(Node, bool)> {
     let fx = rasterfx::raster_fx(n);
     if fx.is_empty() {