server : (UI) add tok/s, get rid of completion.js (#10786)

* get rid of completion.js

* extract chat bubble to a component

* add tok/s info

* sync

* fix BASE_URL

* only extract timings when it's enabled

* fix auto scroll

examples/server/webui/package.json

@@ -17,6 +17,7 @@
     "markdown-it": "^14.1.0",
     "postcss": "^8.4.49",
     "tailwindcss": "^3.4.15",
+    "textlinestream": "^1.1.1",
     "vite-plugin-singlefile": "^2.0.3",
     "vue": "^3.5.13"
   }