Show a basic timeline while the world time is away from live

A bar above the command dock, like a video player's: play and pause on
the left, the world time's date and time in UTC beside it, and Live to
return. It stays hidden while live, so Core looks as before until weather
history is scrubbed or replayed, a host moves the clock, or a link made
away from live is opened. Adds the pause and play_arrow glyphs and the
strings in every catalog.

src/i18n/locales/zh-Hant.json

@@ -2868,5 +2868,8 @@
   "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",
   "Left panels": "左側面板",
-  "Right panels": "右側面板"
+  "Right panels": "右側面板",
+  "World time": "世界時間",
+  "Back to live": "返回即時",
+  "Live": "即時"
 }