Chart on Admin Dashboard Overview

[thaninbew]

view on Figma!

Style the stats chart from barebones and use the new/modified endpoints implemented in #96 (might have to wait, you can just work on styling in the frontend for now)

Acceptance Criteria:

• Manual testing
• Matches Figma - Colorscheme, fonts, etc.
• Use shadcn/ui + tailwind for this. I believe the stats chart in Figma is using shadcn ui
• keep placeholder data for now.

Future:

Once #96 is done, use the endpoint to populate the chart