feat: add LP risk summary panel

[newmattock]

Fixes #32

Summary

• add an LP position risk panel above the funded positions table
• compute positions at risk, capital at risk, and disputed position counts from LP positions
• let metric clicks filter the positions table to at-risk or disputed invoices
• refresh risk-time evaluation every 5 minutes and add pure metric/filter tests

Validation

• npm test -- src/utils/tests/lpRisk.test.ts --reporter verbose
• npx eslint src/utils/lpRisk.ts src/utils/tests/lpRisk.test.ts src/components/LPRiskPanel.tsx src/components/LPPortfolio.tsx
• npm run build
• git diff --check
• local smoke: HEAD /lp returned HTTP 200 on port 3015