Project · a focused card scrolls into view

The board scrolled sideways without a handle, so a card that took
focus past the fold stayed out of sight, ring and all, and Option-Right
could send it into a column nobody saw. The board now tracks its
scroll, and a card that takes focus sets the offset through
layout::bring_into_view from its row's painted box, ring included, once
per focus and again when it lands in another column. The stepping
rules gain tests for left and right keeping a card's place and for the
end of a shorter column.

TASKS.md

@@ -364,3 +364,4 @@ Per-component lines live in `tasks/`. Tags there:
 | T30d | 1 | FAIL | a chosen day outlived the owner's days, and the next render panicked |
 | T30d | 2 | PASS | |
 | T31a | 1 | PASS | |
+| T31b | 1 | FAIL | a focused card past the board's fold stayed out of view; left and right steps that keep a card's place went untested |