Slate AR Perfect

Handle $ARGUMENTS.

Use this when the user wants a Slate v2 surface made genuinely good, not one isolated packet. This is the high-level loop for "perfect pagination", "perfect huge document perf", "perfect editor behavior", and similar asks.

This is the main "absolute best architecture / DX / API / testing / perf" workflow. The user should not need to manually call slate-ar-fast or slate-ar-stabilize after slate-ar-perfect; those are internal or expert override lanes.