Add the layout screen's portfolio board and default color to full palette

The index board grows the parts only a portfolio has: a project rail, a
support row, and a pagination rail restated at the foot of the handset
stack. They mount behind a prop rather than for every board, because the
motion screen reads the same index body through :nth-of-type and a stray
sibling would shift its scenes. Their sheet loads after the boundary,
corner, and depth sheets so it wins ties on source order.

The color strategy question now opens on Full palette.

Prepared with AI assistance (Cursor).

Co-authored-by: Cursor <cursoragent@cursor.com>

picker/components/QuestionScreen.astro

@@ -105,6 +105,7 @@ const tabsAttrs = perSurface ? surfaceTabsAttrs(name) : null;
               phone={phone}
               cursor={slug === 'motion'}
               carry={slug !== 'motion'}
+              portfolioExtras={slug === 'layout'}
             />
           ))}
         </div>