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/zh-Hant.json

@@ -2873,5 +2873,7 @@
   "Play from this scene through the rest of the project": "從此場景開始播放項目中的其餘場景",
   "Play the shot after the selected one, moving on to the next scene when needed": "播放所選鏡頭的下一個鏡頭，必要時進入下一個場景",
   "Edit anchors, data packs and shot details": "編輯錨點、數據包和鏡頭詳情",
-  "Download this scene as JSON or an asset bundle": "將此場景下載為 JSON 或資源包"
+  "Download this scene as JSON or an asset bundle": "將此場景下載為 JSON 或資源包",
+  "Left panels": "左側面板",
+  "Right panels": "右側面板"
 }