Fix source selection after disabling dual output

[aleksandr-voitenko]

The PR fixes the following issue:

Steps:
- Enable dual output mode
- Disable Horizontal canvas in the top right corner settings
- Disable dual output mode

Expected: When sources selected on canvas, they highlighted in the list an vice versa.
Actual: This does not happen. Selection link is lost.

Note: it works again if enable dual output and enable there horizontal canvas. So it must be a pure UI issue.

Reproduction video:

2026-09-04.10-50-58.mp4

Description

Disabling dual output after hiding the horizontal canvas left the Sources list using vertical item IDs while the canvas displayed horizontal items, breaking selection highlighting in both directions.

Use horizontal items consistently when dual output is off, and restrict paired selection and highlight mapping to dual-output mode. Preserve saved display visibility preferences when dual output is re-enabled.

Added regression tests covering selection in both directions after disabling dual output with horizontal hidden or visible, plus restoration of display preferences.

[bundlemon]

BundleMon

Files added (4)

Status	Path	Size	Limits
✅	renderer.(hash).js	+10.53MB	-
✅	vendors~renderer.(hash).js	+4.67MB	-
✅	updater.js	+115.29KB	-
✅	guest-api.js	+40.23KB	-

Total files change +15.34MB

Final result: ✅

View report in BundleMon website ➡️

---

Current branch size history