feat: implement middleware authentication, secure secret redaction, a…

[Alhaji-naira]

Description

This PR addresses critical performance bottlenecks and security vulnerabilities. It improves initial load times by code-splitting heavy chart libraries, stabilizes UI rendering for massive property lists, and enforces secure data handling for both client routing and error reporting.

🚀 Performance Optimizations

• Deferred Heavy Chart Libraries (Closes [Perf] Defer recharts / d3 charts to dynamic imports above-the-fold #650):

  • Created a reusable withLazyChart HOC combining next/dynamic and IntersectionObserver.
  • Lazy-loaded TransactionAnalytics and MortgageCalculator to prevent recharts and d3 from blocking the main thread eagerly.
  • Removed duplicate inline chart components from TransactionHistory.tsx to ensure proper code-splitting.

• Virtualized Property Grids (Closes [Perf] Virtualize large Web3 property grids with @tanstack/react-virtual #651):

  • Built a new VirtualizedPropertyGrid component powered by @tanstack/react-virtual.
  • Replaced the eager grid rendering in SearchResults.tsx (which powers the /properties route) with the virtualized version, solving scroll stuttering on lower-end devices.
  • Mapped aria-setsize, aria-posinset, and role="listitem" onto virtual rows to preserve 100% screen reader accessibility.

🔒 Security Enhancements

• Strict JWT Validation (Closes [Security] Validate JWT/auth-token in middleware.ts (currently only checks cookie existence) #652):

  • Upgraded the auth-token middleware check to perform full cryptographic signature and expiry validation using jose (jwtVerify), closing an authentication bypass vulnerability.
  • Included a 15-second clock tolerance for distributed servers and updated client-side token parsing in useAuth.ts.
  • Added robust unit test coverage in middleware.test.ts.

• Automated Secret Redaction (Closes [Security] Strip secrets from error-reporting context (privateKey, mnemonic, cookies) #654):

  • Implemented a recursive payload sanitization utility (redactSecrets) in src/utils/secretRedaction.ts leveraging a WeakSet to safely handle circular references.
  • Integrated the redaction layer into sendToAnalytics (src/utils/errorReporting.ts) to strip sensitive keys (jwt, private_key, token, etc.) from contextual error data and stack traces before transmission.

Testing & Validation

• ✅ Verified complete pipeline health (npm run lint and npm test).
• ✅ Mocked the @tanstack/react-virtual grid in SearchResults.test.tsx to ensure tests continue to pass gracefully.
• ✅ Unit tests provided for new middleware authentication boundaries and secret redaction functions.

Reviewer Notes

Please ensure that the AUTH_SECRET environment variable is correctly configured in staging and production, as the strict middleware validation will safely block users if the secret is missing.

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[nanaf6203-bit]

LGTM