A section stayed on with nothing in the browser to switch it off; only the
viewport's context menu had Remove Section. While there is one, the browser
now has an Analysis folder listing it. Its eye (and the folder's) hides the
section and shows it again on the same plane; a double-click or Edit Section
Analysis opens the dialog, and Delete removes it. Browser rows with an eye
publish an `eye:<label>` handle for automation.
Fixes#822
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>