Dashboard: a focused tile's Left and Right, and a control's own arrows, tested

The arrows test also moves a focused tile right and back; a new test
focuses a button inside a card and shows its arrows leave the tiles.
A card given for a key with no tile fails loud, in both layouts.

TASKS.md

@@ -395,3 +395,4 @@ Per-component lines live in `tasks/`. Tags there:
 | T33c | 3 | PASS | |
 | T33d | 1 | FAIL | text fields never painted a highlight's wash; a tile's value ran past 280px; a stray + read as a hex digit; the WCAG thresholds, an exit's badge, a stopped row's load and the meter's clamp untested |
 | T33d | 2 | PASS | |
+| T34 | 1 | FAIL | a focused tile's Left and Right, and the guard that leaves arrows to a focused control inside a card, untested |