feat: Use search endpoint for finals filtering instead of text search

[tsurbs]

Summary

This is a pull request for branch finals-use-search-endpoint.

This PR refactors the finals search functionality to use the existing /courses/search backend endpoint instead of client-side text filtering on the finals.json data.

Changes

New File: apps/frontend/src/app/api/finals.ts

• Added useFetchFinalsSearch hook that calls the /courses/search endpoint with keywords
• Returns a list of matching courseIDs from the backend's full-text search

Updated: apps/frontend/src/components/finals/FinalsViewer.tsx

• Imports the new useFetchFinalsSearch hook
• Uses React Query to fetch search results when user types in the search box
• Filters the finals.json data based on matching courseIDs from the search API
• Standardizes course IDs (e.g., 48321A -> 48-321) for proper matching
• Maintains backward compatibility with the "own courses" filtering feature

Why?

Previously, the finals search was using client-side text filtering on the course code field in finals.json. This was limited because:

1. It only searched the course code, not the course name or description
2. Users couldn't find courses by course name (e.g., "Calculus" wouldn't find 21-120)

Now, the search uses the backend's full-text search which indexes:

• Course names
• Course descriptions
• Course IDs

This provides a much better search experience while still maintaining the local finals data for fast filtering of results.

Testing

• Type checking passes (no new TypeScript errors)
• The logic properly handles:
  • No search query (shows all finals)
  • Search with results (filters finals by matching courseIDs)
  • Search with no results (shows empty state)
  • Own courses filtering combined with search

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Branch: finals-use-search-endpoint
Create PR at: https://github.com/ScottyLabs/cmucourses/pull/new/finals-use-search-endpoint