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.

scripts/format-scope.json

@@ -1122,5 +1122,7 @@
   "src/ui/kit/UiRail.test.mjs",
   "src/testSupport/vueDom.mjs",
   "src/testSupport/vueLoader.mjs",
-  "src/testSupport/registerVue.mjs"
+  "src/testSupport/registerVue.mjs",
+  "src/ui/panelNavigation.test.mjs",
+  "src/ui/stores/panels.test.mjs"
 ]