Decide bottom panel behavior when no link is selected

[wilhel1812]

Current state

When no link is selected, the bottom panel shows a placeholder with no toolbar and no hide button.

Discuss

Decide whether to:

• hide the panel completely in this state, or
• add a toolbar.

An argument for keeping the panel is that it could show multi-site information.

[wilhel1812]

Starting implementation with locked scope: keep the empty Profile panel visible, reuse the documented PanelToolbar shell for both no-analyzable-Path and 3+ selected Site guidance states, retain existing guidance text, and expose only the existing row hide/size controls while empty. Panorama empty-state behavior remains out of scope.

[wilhel1812]

Merged PR #903 into staging after local verification and required PR checks passed. Status moved to in-staging while the automatic staging deployment is monitored and the live empty Profile panel behavior is verified.

[wilhel1812]

Staging verification complete for commit 30abd78f (v0.20.0-beta+30abd78f). Automatic Deploy LinkSim Pages / deploy-staging run 26840011740 completed successfully. Live check on https://staging.linksim.link confirmed the cleared-selection bottom panel shows Path Profile, the existing Hide Profile panel control, and the guidance text, while reverse-direction and full-screen actions are absent. Issue remains in-staging pending staging sign-off.

[wilhel1812]

Staging feedback follow-up started. Locked scope: keep the bottom-panel empty toolbar titleless because the panel supports more than Path Profile, keep the toolbar aligned at the panel top like Path Profile and Panorama modes, and revise the guidance to mention selecting one Site for Panorama as well as two Sites or a saved Path for Path Profile analysis.