Task card was the outlier in the Knowledge view: half-width fade-to-
transparent gradient bar while note/list use full-width two-stop
gradients, and the type badge was purple while the border+bar were gold.
- k-card--task::before: full width with gold→amber gradient (#d4a017
→ #fbbf24) matching the two-stop pattern
- badge--task: switched from purple to amber so the badge matches
the card chrome