Keyboard access for the Save options menu

Builderius draws the Save button’s dropdown trigger inside the Save button itself, where no keyboard or screen reader can reach it — the Save to Development / Publish to Live menu is mouse-only. This replaces that trigger with a real button beside Save (announced as a menu, arrow keys inside, Escape to close). Experimental and off by default: it restyles a core control, and the proper fix belongs in Builderius (reported upstream) — this is a stopgap for keyboard users until then.