Refine inspector for multi-site selection behavior

[wilhel1812]

Summary\nRefine the inspector UX to match the new selection model across no-selection, single-site, two-site, and multi-site states.\n\n## Goals\n- Make active context explicit (none, selected site, selected site pair, saved link, library marker)\n- Show only relevant actions per context (for example Save Selected Link, Add To Simulation, Remove From Simulation)\n- Keep deselected state neutral (no implicit active link context)\n- Improve clarity around site-pair vs saved-link inspector copy\n- Keep terminology consistent: Simulation, Site, Library, Path, Channel\n\n## Notes\n- Keep this issue in until final wording/scope is agreed\n- Related: #104

[wilhel1812]

Created from Issue #104 completion pass to track inspector refinements for the new selection model. Keeping this in pending-discussion until wording/scope is finalized.