feat: Added RunLLM chat widget for Ray docs; disabled regular AI chatbot

[cszhu]

Description

This PR integrates the runLLM chat widget into the Ray documentation site, replacing the existing custom "Ask AI" widget. Our new widget appears in the bottom-left corner of all doc pages and will answer questions powered by our runLLM agent.

Changes:

• Added runllm-widget.js to load and configure the runLLM widget
• Updated conf.py to include the widget script on all pages
• Disabled the existing custom "Ask AI" widget (assistant.js)
• Widget configured with:
  • Assistant name: "Ray RunLLM Bot"
  • Position: Bottom right
  • Keyboard shortcut: Mod+j (Cmd+J / Ctrl+J)

Related issues

N/A - New feature addition

Additional information

Testing:

• Widget can be tested locally by:
  • building docs with DOC_LIB=data sphinx-build -b html -d _build/doctrees source _build/html
  • or serving with python -m http.server 8000 -d _build/html
• Widget will appear on all documentation pages once deployed.

Screenshots:
Examples of the widget on various pages:

Example of widget open (opens an overlay):

The existing custom "Ask AI" widget has been disabled but the code remains commented out in case we need to revert.

[gemini-code-assist]

Code Review

This pull request introduces the RunLLM chat widget to the Ray documentation, replacing the previous 'Ask AI' chatbot. The changes involve adding a new JavaScript file to dynamically load the widget, and updating the Sphinx configuration to include this new script while disabling the old one. The implementation is mostly correct, but I've identified a few areas for improvement in the new JavaScript file concerning best practices, correctness, and maintainability. Specifically, I've suggested using const over var, correcting an invalid attribute value for crossorigin, extracting a magic number into a constant, and simplifying the script by removing a redundant event listener.

[cszhu]

@cristianjd @maxpumperla Just saw you two worked on the last version of Ask AI so requested a review! Msg me if you have any questions :)

[crypdick]

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