The sticky bulk-action bar (#443) was visible on every tab whenever the
selection was non-empty. On Y3R C4LL / SYST3M / SCH3DUL3S the operator
sees a floating bar without the agent cards next to it for cross-
reference — which is what mara called out in #596.
Fix: gate the bar on `document.body.dataset.activeTab === 'swarm'` in
addition to the existing non-empty-selection check. Selection state
itself stays in memory, so the bar reappears on return to SW4RM if any
agents are still ticked. The `activateTab` hook now sets the data
attribute and re-runs `renderSelectionBar` so the toggle takes effect
on hashchange without waiting for the next SSE update.
1ae939499c