TiDB.ai Chatbot improvements

• Back to top button. This is useful to read the answer from beginning as the generated answer will scroll automatically to the bottom.
• Perhaps replace the following with flags to represent languages:
  
• The placement of Ask TiDB.ai seems to indicate that you can type the prompt in the search, and then it will run on TiDB.ai, but the button is actually a link to the TiDB.ai dialog box, so you need to type the prompt again.
  
• Highlight Ask TiDB.ai with a bit more fanfare indicating that it's new.
• The placement of the prompt seems awkward, with lots of empty space between the top of the screen and where you enter the prompt. This is exacerbated by the very faint border around the prompt entry, which makes it difficult to see:
  
• All the status indicators of the LLM execution seem extraneous and confusing. I think a dynamic status indicator (along with a performance boost in order to display results faster) seems preferable:
  

No files or tests are named. Start by locating the TiDB.ai Chatbot UI and reproducing the listed search, prompt, scrolling, language-display, and status-indicator behaviors. Define the scope with maintainers first; done should be an agreed and tested set of improvements from the checklist.