fix(ui): chat side bar

[abhix4]

fixes :
sizing issues , message previews and paddings

[jazzberry-ai]

Bug Report

Name	Severity	Example test case	Description
Incomplete Markdown Removal in Chat Sidebar	Medium	Send a chat message containing a blockquote, list item, or ordered list item. Observe that the chat sidebar displays the raw markdown.	The regex used in generateMessagePreview to remove markdown formatting is incomplete and does not handle blockquotes, list items, or ordered list items. This results in unformatted markdown being displayed in the chat sidebar, which degrades the user experience.

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[abhix4]

@ArnavAgrawal03 here also , the font is my system's default