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.

src/i18n/locales/es.json

@@ -3013,5 +3013,7 @@
   "Play from this scene through the rest of the project": "Reproduce desde esta escena hasta el resto del proyecto",
   "Play the shot after the selected one, moving on to the next scene when needed": "Reproduce el plano posterior al seleccionado y pasa a la siguiente escena si hace falta",
   "Edit anchors, data packs and shot details": "Edita anclas, paquetes de datos y detalles de los planos",
-  "Download this scene as JSON or an asset bundle": "Descarga esta escena como JSON o como paquete de recursos"
+  "Download this scene as JSON or an asset bundle": "Descarga esta escena como JSON o como paquete de recursos",
+  "Left panels": "Paneles izquierdos",
+  "Right panels": "Paneles derechos"
 }