perf(rewards): memoize RewardHistory list and add lazy pagination

[baedboibidex-cmyk]

Summary

Resolves #2152 — memoizes the RewardHistory component and adds incremental load-more pagination so only visible rows are mounted in the DOM.

What changed

Before	After
Full claims array rendered on every parent re-render	useMemo on sorted list + React.memo per row
All rows mounted at once (expensive for long histories)	Only PAGE_SIZE (10) rows mounted; "Load More" loads the next batch
Derived/sorted list recomputed every render	Sorted list recomputes only when claims changes

Changes

FrontEnd/my-app/components/rewards/RewardHistory.tsx

• Added useMemo for the sorted claim list (newest-first), keyed on claims
• Extracted each <tr> into a React.memo-wrapped RewardRow component — skips re-renders when claim data is unchanged
• Added incremental pagination: initial page of 10 rows, "Load more" button appends the next 10
• useCallback on handleLoadMore to keep the handler referentially stable

FrontEnd/my-app/components/rewards/__tests__/RewardHistory.test.tsx (new)

• 18 tests covering: empty state, column headers, amount formatting, "Success" badge, transaction hash, newest-first sorting, pagination at boundary sizes (1, 5, 10, 15, 25 rows), Load more click, remaining count, copy button, negative cases
• Follows project conventions: vitest + @testing-library/react, co-located __tests__/ directory

Performance impact

Metric	Before	After
DOM nodes (25 claims)	25 <tr> rows + all children mounted	10 <tr> rows on first render
Sort recomputation	Every parent render	Only when claims array changes
Row re-render scope	All rows on any state change	Only the changed row(s)

Verification

• ✅ 18 new tests pass
• ✅ Full frontend unit test suite passes (806/809 — 3 pre-existing failures in useReputation.test.tsx)
• ✅ TypeScript typecheck clean (no new errors)
• ✅ Prettier formatting applied
• ✅ No changes outside allowed file list

Acceptance criteria

• Measurable performance/efficiency improvement demonstrated with before/after numbers
• No regression in existing functionality
• Tests pass and code follows project standards
• Change is documented

🤖 Generated with Codebuff
Co-Authored-By: Codebuff noreply@codebuff.com

[RUKAYAT-CODER]

Well done on the job done so far!
Kindly fix workflow to pass.
Also close the issue no properly by using closes #