Add tests for MarketplaceFilters and MarketplaceGrid filtering and empty states

[1nonlypiece]

📌 Description

src/components/MarketplaceFilter/MarketplaceFilters.tsx and
src/components/MarketplaceGrid.tsx drive the marketplace browsing experience,
and design/marketplace-search/ documents many states (default, recent
searches, typeahead, active query, empty results). Only
tests/components/MarketplaceHeader/ is currently covered; the filters and grid
have no tests.

This issue adds tests for filter interactions and grid rendering, including the
empty-results state.

Goal: verify marketplace filters apply correctly and the grid renders
listings, loading, and empty states as specified.

🎯 Requirements and Context

• Test that changing filters emits the expected query/state changes.
• Test grid rendering for: populated listings, loading
  (MarketplaceGridSkeleton.tsx), and empty results.
• Mirror states from design/marketplace-search/search-flow.md.
• Assert accessible labelling of filter controls.

🛠️ Suggested Execution

1. Create a branch

git checkout -b feature/marketplace-filters-grid-tests

2. Implement changes

• Add tests/components/MarketplaceFilters.test.tsx and
  tests/components/MarketplaceGrid.test.tsx.

3. Test and commit

• Run npm test.
• Edge cases: no listings, filter reset, multiple active filters, loading→empty
  transition.

Example commit message

test: cover MarketplaceFilters interactions and MarketplaceGrid states

✅ Guidelines

• Minimum 95% test coverage on the targeted components.
• Clear, descriptive test names.
• Timeframe: 96 hours.

🏷️ Labels

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

💬 Community & Support

• Join the CommitLabs contributor Discord: https://discord.gg/WV7tdYkJk
• Introduce yourself before starting to avoid duplicate work.
• Maintainers triage actively and review fast.

[BowenMilner]

Submitted PR: #608

Payment details can be provided privately if this is accepted.