Shape Format: Shape Effects — shadow, glow and soft edges (#275)

Shapes and text boxes get an effects model (outer shadow with colour,
transparency, blur, distance and angle; glow with colour, size and
transparency; soft-edge radius), the shape.effects command (presets,
custom values or null per effect, applied to every selected shape,
undoable, hostile numbers clamped), screen and PDF rendering with the
same banded approximation of a blur, DOCX a:effectLst read/write
(outerShdw, glow, softEdge) with a matching wp:effectExtent, and a
contextual Shape Format tab with Shape Fill, Shape Outline and Shape
Effects (Shadow, Glow, Soft Edges submenus) plus Arrange.

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

docs/parity.md

@@ -2,7 +2,7 @@
 
 Generated by `cargo xtask parity` (`wordcraft-cli parity --markdown`): the word-processor feature catalog (`crates/engine/src/catalog.rs`) compared with the live command registry.
 
-**378 of 428 catalog features have commands (88.3%).**
+**379 of 428 catalog features have commands (88.6%).**
 
 | Tab | Live | Total |
 |---|---|---|
@@ -21,7 +21,7 @@ Generated by `cargo xtask parity` (`wordcraft-cli parity --markdown`): the word-
 | Table Layout | 28 | 30 |
 | Equation | 21 | 22 |
 | Picture Format | 13 | 13 |
-| Shape Format | 2 | 6 |
+| Shape Format | 3 | 6 |
 | Header & Footer | 5 | 5 |
 | Editing | 23 | 24 |
 | Tools | 3 | 6 |
@@ -96,7 +96,6 @@ Generated by `cargo xtask parity` (`wordcraft-cli parity --markdown`): the word-
 
 ### Shape Format
 
-- Shape Styles › Shape Effects (`shape.effects`)
 - Text › Text Direction (`shape.textDirection`)
 - Text › Align Text (`shape.alignText`)
 - Text › Create Link (`shape.link`)