feat(ui): add a desktop panel rail to each sidebar

Each side stack hosts a Vue rail listing its panels; selecting one opens it
through PanelChrome. The shell owns one Vue runtime and Pinia instance, and a
panel store mirrors each side's panels from the DOM. The rail hides with its
stack, in Cockpit, clean view and recording, and on phones. Panels without a
catalog entry get a generic item, and Data Layers leaves the rail while the
f shortcut hides it.

docs/UI-OWNERSHIP.md

@@ -11,6 +11,7 @@ scene playback and voice. It delegates; new behavior belongs with its owner.
 | `cockpitCoordinator.js` | Cockpit entry/rollback, readouts and the single Display portal |
 | `visualSettings.js` | Effects, detection overrides, visual restoration and render-loop lifetime |
 | `panelChrome.js` | Disclosure, docking, layout and Cockpit panel restoration |
+| `panelNavigation.js` | Desktop panel rails: each side's offered panels and the open one |
 | `aircraftDisplay.js` | Shared commercial/military 3D display preferences and controls |
 | `layerBindings.js` | Data-manager attachment, selected-tracker adoption and camera-entry listeners |
 | `displayBindings.js` | Keyboard/display subscriptions and frame-rate monitor lifetime |