* feat: Add a new chat button with a confirmation modal
* Fix for PR comments
* fix: add error handling and proper cleanup in handleNewChat
- Add try-catch for localStorage operations to handle quota exceeded,
private browsing, and other storage errors
- Use handleFileChange([]) instead of setFiles([]) to properly clear
pdfData Map alongside files
- Only show success toast when localStorage operations succeed
- Show warning toast if localStorage fails but chat state is cleared
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Co-authored-by: Dayuan Jiang <jdy.toh@gmail.com>
