Implement dispute rate metric on stats page

[Marvell69]

The dispute rate (disputed / total funded) is a key protocol health indicator. A low dispute rate signals trustworthy participants; a rising rate may indicate fraud or oracle issues.

Requirements and context

• Metric card on stats page: "Dispute Rate: X%" (last 30 days)
• Colour coding: green (<1%), amber (1–5%), red (>5%)
• Tooltip: how dispute rate is calculated
• Historical sparkline: dispute rate trend over 90 days
• Computed from contract event data

Suggested execution

git checkout -b feat/dispute-rate-metric

• Create <DisputeRateCard /> component
• Compute dispute rate from event data
• Add sparkline using recharts
• Write computation and colour threshold tests

Example commit message
feat: add dispute rate metric card with colour coding to stats page

[0xBernny]

@0xBernny has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

because I can

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[drips-wave]

Congratulations, @0xBernny! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 2, 2026.

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