Add a chart tooltip with formatted values

[arisu6804]

Summary

Add a chart tooltip with formatted values.

Context

Tracking issue for the RemitFlow frontend. Open to contributors.

Acceptance criteria

• Implement the change described above
• Add or update automated tests
• Update the relevant documentation

[Hollujay]

I would like to work on this issue because I will get it done.

[arisu6804]

Assigned, @Hollujay 📊 Chart tooltips with formatted values — nice place to start on the chart set. https://t.me/+8DgYV9HrNaA1Yjg1

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Official Campaign | FWC26 campaign!

@Hollujay's PR #264 was approved and merged by @arisu6804.

🏆 @Hollujay: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (328 total points). Track your full progress on GrantFox.

👏 Great work, @Hollujay! Keep contributing to RemitFlow.