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/fr.json

@@ -3013,5 +3013,7 @@
   "Load scenes from an exported JSON file": "Charger des scènes depuis un fichier JSON exporté",
   "Download the timing log of the last play": "Télécharger le journal de minutage de la dernière lecture",
   "Edit anchors, data packs and shot details": "Modifier les ancres, les paquets de données et les détails des plans",
-  "Download this scene as JSON or an asset bundle": "Télécharger cette scène en JSON ou en archive de ressources"
+  "Download this scene as JSON or an asset bundle": "Télécharger cette scène en JSON ou en archive de ressources",
+  "Left panels": "Panneaux de gauche",
+  "Right panels": "Panneaux de droite"
 }