Memoize and virtualize MyCommitmentsGrid and MarketplaceGrid to remove large-list render jank

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📌 Description

src/components/MyCommitmentsGrid.tsx and src/components/MarketplaceGrid.tsx
render potentially large lists of commitment cards (MyCommitmentCard.tsx,
MarketplaceCard.tsx). The cards are not memoized and the grids re-render fully
on filter/sort changes, which causes jank as result sets grow — the
design/dashboard-overview/responsive-layouts.md and marketplace specs assume
smooth scrolling and filtering.

This issue improves large-list rendering performance via memoization and
windowing.

Goal: filtering and scrolling large commitment/marketplace lists stays
smooth, with cards memoized and off-screen rows not paying render cost.

🎯 Requirements and Context

• Wrap MyCommitmentCard.tsx and MarketplaceCard.tsx in React.memo with
  stable props/keys.
• Memoize derived filtered/sorted lists (useMemo) in the grid components.
• Add list virtualization/windowing for large result sets (lightweight,
  dependency-conscious; document any new dependency).
• Preserve existing skeleton/empty states
  (MyCommitmentsGridSkeleton.tsx, MarketplaceGridSkeleton.tsx).
• Measure before/after with a large mock dataset.

🛠️ Suggested Execution

1. Create a branch

git checkout -b feature/grid-perf-virtualization

2. Implement changes

• Update the grid + card components as above.
• Add tests/components/MyCommitmentsGrid.perf.test.tsx asserting memoized cards
  do not re-render when unrelated state changes.

3. Test and commit

• Run npm test.
• Edge cases: empty list, single item, very large list, rapid filter toggling.

Example commit message

perf: memoize and virtualize MyCommitments and Marketplace grids

✅ Guidelines

• Minimum 95% test coverage on changed rendering logic.
• Clear documentation of measured improvement and any new dependency.
• Timeframe: 96 hours.

🏷️ Labels

type-performance · area-frontend · type-testing · MAYBE REWARDED · GRANTFOX OSS · OFFICIAL CAMPAIGN

💬 Community & Support

• Join the CommitLabs contributor Discord: https://discord.gg/WV7tdYkJk
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