M13.5: stroke taper/wave/multi-dashes, radial gradient highlight, variable-width mask feather, adaptive motion-blur samples

Shapes (SHP-2): Stroke Taper (pixels/percent start/end length, width, ease) and
Wave (amount, pixels/cycles, wavelength, phase) rendered as a variable-width
outline; Dash 2/Gap 2/Dash 3/Gap 3 (shape.dashes.add/remove, timeline +/-
buttons); radial gradient Highlight Length/Angle as a focal gradient.
Masks (MSK-1): mask feather points on the Mask Path (mask.featherPoint.*,
Mask Feather tool add/drag), per-point signed radius and tension, rendered
from the signed distance to the path; carried through vertex edits.
Motion blur (LYR-10): Adaptive Sample Limit comp setting; 2D layers take one
sample per pixel of shutter travel between Samples Per Frame and the limit.

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

crates/expr/src/runtime.rs

@@ -469,7 +469,13 @@ pub fn to_value(out: &Out, current: &Value) -> Result<Value, String> {
                     v.resize(n, [0.0; 2]);
                     v
                 };
-                Value::Path(effectcraft_keyframe::ShapePath { vertices: points.clone(), in_tangents: fit(ins), out_tangents: fit(outs), closed: *closed })
+                Value::Path(effectcraft_keyframe::ShapePath {
+                    vertices: points.clone(),
+                    in_tangents: fit(ins),
+                    out_tangents: fit(outs),
+                    closed: *closed,
+                    feather: Vec::new(),
+                })
             }
             _ => return Err("Error: expression result must be a path".into()),
         },