fix: UI improvements

[morozRed]

Summary

• Add animation to "Advanced" section opening (closes Extension: Advaned Toggle Animation isn't perfect #26)
• Closes Chat UI doesn't disappear if disabled in settings. #25, was not able to reproduce the issue
• Center page title in the sidebar
• Consistent copy icons across the app

Centered title:

Copy icons usage:

[steipete]

Landed via temp rebase onto main.

• Gate: pnpm -s check and pnpm -s build
• Land commit: 6076809
• Merge commit: 3e9b4ad

Thanks @morozRed!