Dropdown: designer follow-up (post-#16)

[lifeiscontent]

From @bhaveshraja's review on #16 (merged 2026-06-09):

• Divider: only 1 line between search and the "Add label" item (not 2, designer correction to the original feedback).
• "View all": clicking should expand the rest of the list inline (currently a styled no-op in the demo).
• Filters header-clickable-to-collapse, designer confirmed working, no action.

Source: #16 comment (2026-06-09 18:56).

[lifeiscontent]

Addressed in #48:

• Labels demo now shows a single divider between the search field and the "Add label" row (removed the extra line; the sticky search's own bottom rule is the one divider).
• "View all" in the Filters demo now expands the remaining rows inline (toggling to "Show less"), keyboard-accessible via the menuitem with aria-expanded.

Verified in Storybook (both demos rendered), vp check + tests (3x) + build all green.