[feature] Embed assistants

[mishig25]

Description

Users can now create tools and connect their tools to their assistants (read here), making for use cases such as: create an assistant that queries your websites and chats about your website.

This PR adds an ability where users can embed their assistants on their websites.

Step1: under assistants settings, there will be script tag that can be put on a website's html head section.

Step2: HF Chat button will appear on the bottom right section of your website.

Step3: When you click on HF Chat button, a chat window modal with minimal hf/hf-chat chrome will appear

Testing locally

1. follow the latest readme on how to run chat-ui locally
2. read this comment

Reviewing

when reviewing make sure to click Hide whitespace to see the actual diff

Screen recording

https://github.com/user-attachments/assets/6508905e-be8b-4dc4-9f49-72203d801263

it may look bit confusing in the video because I'm embedding hf-chat inside hf-chat locally for testing purposes. but you can imagine the hf-chat modal being embedded on any arbitrary website