feat(ui): right rail as vertical tabs with sideways labels

Replace the right rail's collapsed launcher cards with a vertical tab
strip: one sideways tab per panel, the open panel beside it, at most one
panel open in every HUD layout. The panels' collapsed classes stay the
source of truth; the strip mirrors them and routes every change through
setPanelCollapsed, so persistence and share links are unchanged. Phones
keep the sheet shell.

Five presentations, picked with data-rail-tabs on the rail: cards-down
(default), cards-up, spine, icons and minimal.

The one-owner rule, previously Cyber-only, now applies to every desktop
layout, so the right rail's Tactical auto-collapse retry path is dead and
removed. Escape inside a panel returns focus to the panel's tab.

Co-Authored-By: Claude Fable 5.1 <[email protected]>

src/ui/mobileShell.js

@@ -208,7 +208,7 @@ export function initMobileShell({
     return (
       classes.contains('collapsed') &&
       !classes.contains('layout-auto-collapsed') &&
-      !classes.contains('cyber-accordion-collapsed')
+      !classes.contains('rail-owner-collapsed')
     );
   };