#1144: Live Corners round corners between curved segments too

A corner is now any anchor that isn't smooth where two sides meet at an
angle, straight or curved, as in Illustrator. The cut meets each side at
its setback measured along the curve, leaves both sides along their
tangents there, and each curved side is trimmed to what the cuts at its
ends leave of it. The largest radius is still the one taking the cut
halfway along the shorter side, measured along the curve. Corners
between straight sides draw exactly as before.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/engine/src/cmd/object.rs

@@ -196,7 +196,7 @@ pub fn specs() -> Vec<CommandSpec> {
             "Live Shape Properties",
             [],
             None,
-            "{id?, ids?, radius?: pt, kind?: \"round\"|\"invertedRound\"|\"chamfer\", corners?: [i…], items?: [{id, corners?: [i…]}] (several objects, each with its own corners, in place of ids and corners: the canvas's corner widgets across a selection), sides?: n, polygonAngle?: degrees (counterclockwise from its first vertex straight up), polygonRadius?: pt (centre to vertex), sideLength?: pt (sets the radius), makeSidesEqual?: true (a polygon scaled unevenly: drops the uneven scale and shear, keeping its centre, angle and mean radius), pieStart?, pieEnd?: degrees (an ellipse's pie, counterclockwise from 3 o'clock; 0 to 360 is the whole ellipse), invertPie?: true (swaps them: the other part of the ellipse)} (Live Corners on any path: radius and kind set its corners (anchors without handles between two straight sides): `corners` (anchor indices of the path with its corners uncut, counting every subpath's anchors in order: a rectangle's 0 top-left, 1 top-right, 2 bottom-right, 3 bottom-left; a polygon's from the first vertex clockwise), else the corners with a Direct-Selected anchor, else every corner; each radius is drawn no larger than half the corner's shorter side allows; a path that isn't a live shape keeps its uncut outline so its corners stay editable, and is plain again once none is cut; sides: a polygon's, which keep the radius they shared; the polygon params apply in that order: sides, makeSidesEqual, polygonAngle, then sideLength or else polygonRadius)",
+            "{id?, ids?, radius?: pt, kind?: \"round\"|\"invertedRound\"|\"chamfer\", corners?: [i…], items?: [{id, corners?: [i…]}] (several objects, each with its own corners, in place of ids and corners: the canvas's corner widgets across a selection), sides?: n, polygonAngle?: degrees (counterclockwise from its first vertex straight up), polygonRadius?: pt (centre to vertex), sideLength?: pt (sets the radius), makeSidesEqual?: true (a polygon scaled unevenly: drops the uneven scale and shear, keeping its centre, angle and mean radius), pieStart?, pieEnd?: degrees (an ellipse's pie, counterclockwise from 3 o'clock; 0 to 360 is the whole ellipse), invertPie?: true (swaps them: the other part of the ellipse)} (Live Corners on any path: radius and kind set its corners (anchors that aren't smooth, where two sides, straight or curved (#1144), meet at an angle): `corners` (anchor indices of the path with its corners uncut, counting every subpath's anchors in order: a rectangle's 0 top-left, 1 top-right, 2 bottom-right, 3 bottom-left; a polygon's from the first vertex clockwise), else the corners with a Direct-Selected anchor, else every corner; each radius is drawn no larger than half the corner's shorter side allows; a path that isn't a live shape keeps its uncut outline so its corners stay editable, and is plain again once none is cut; sides: a polygon's, which keep the radius they shared; the polygon params apply in that order: sides, makeSidesEqual, polygonAngle, then sideLength or else polygonRadius)",
             has_selection,
             set_live_shape
         ),