Tighten Plugins group header, add tooltip, and swap icon order

[chriskmnds]

Overview

The Plugins group header should read as a compact section header with clear controls, not as an oversized menu row.

This covers three related header refinements:

• Tighten Plugins group header, remove hover, adjust height and spacing.
• Add tooltip to the Plugins section edit icon on hover.
• Swap icon order in Plugins header, edit on left, chevron on right.

Behavior

• The header should not show the same hover treatment as a normal sidebar item.
• Header height and spacing should align with the intended section-header treatment.
• The edit/customize icon should have a discoverable hover tooltip.
• The edit icon should sit before the chevron so the two controls read in the intended order.

Why

The Plugins header carries section structure plus controls. If it looks like a normal row, users may mistake it for a destination instead of a grouping surface with edit and expand actions.