89f9375bc0
Adds a rebindable 'session.archive' keybind action (shipped unbound, like session.togglePin) plus an ⌥+⇧-click gesture on sidebar session rows, extracted into a pure, unit-tested click resolver so modifier precedence (⌥⇧ archive vs ⇧ pin vs ⌘/⌃⇧ new window) stays correct. Salvaged from #59759. Closes #59308.