feat(ui): keep one side panel open per desktop sidebar in every HUD layout

The Cyber accordion now applies to both sidebars and every HUD layout:
opening a side panel collapses its peers, the layout normalizes restored
state to one owner, and collapsed panels are hidden on desktop. Phones keep
showing several panels per sheet.

src/ui/panelRailGeometry.js

@@ -60,19 +60,3 @@ export function resolveHudRailLayout({
     constrained: panelHeight > availableHeight,
   };
 }
-
-/**
- * Tactical HUD gives an expanded right-rail panel the whole control lane.
- * Other HUD layouts keep collapsed launchers visible for quick switching.
- *
- * @param {object} input Current rail state.
- * @param {string} input.hudVariant Active HUD layout variant.
- * @param {boolean} input.hasExpandedPanel Whether any rail panel is expanded.
- * @returns {boolean} Whether collapsed sibling launchers should be hidden.
- */
-export function shouldHideCollapsedRightPanels({
-  hudVariant,
-  hasExpandedPanel,
-}) {
-  return hudVariant === 'tactical' && Boolean(hasExpandedPanel);
-}