feat: build LP invoice marketplace

[newmattock]

Fixes #19

Summary

• add a /marketplace route for LPs to browse pending invoices
• render marketplace cards with amount, token, discount/yield, due date, submitter, reputation, and wallet-gated Fund Invoice CTAs
• add token/yield/amount/reputation filters, yield/amount/due-date sorting, 20-item pagination, and skeleton/error/empty states
• include focused marketplace utility and page tests
• carry narrow current-main build fixes for governance status typing and related TypeScript compatibility issues

Validation

• npm test -- src/utils/__tests__/marketplace.test.ts app/marketplace/__tests__/MarketplacePage.test.tsx --reporter verbose
• npm run lint -- app/governance/page.tsx src/utils/federation.ts src/utils/evidence.ts src/components/TokenSelector.tsx app/marketplace/page.tsx app/marketplace/__tests__/MarketplacePage.test.tsx src/components/InvoiceMarketplaceCard.tsx src/utils/marketplace.ts src/utils/__tests__/marketplace.test.ts
• npm run build
• git diff --check
• local smoke: curl -I http://localhost:3027/marketplace returned HTTP/1.1 200 OK

Notes

• The page uses the existing getAllInvoices() contract read, then filters/sorts/paginates client-side because no dedicated marketplace pagination contract method exists in the current frontend API.