Select: multiple mode closes the dropdown after every selection #490

Bug

In Select with multiple enabled, choosing an option immediately closes the dropdown. The user must reopen it for every additional selection — picking 5 options costs 10 clicks. Clicking an already-selected option in the list also does nothing (no deselect); removal is only possible via the badge close button.

Root cause

handleMultiSelect in src/components/select/select.tsx unconditionally calls setIsOpen(false) after updating the value, and early-returns for already-selected values.

Expected

• multiple: dropdown stays open across successive selections; clicking a selected option deselects it (toggle) without closing.
• Escape and outside click (Floating UI useDismiss) still close it.
• Single mode unchanged: closes on select.