Implement advanced search with full-text search #23
Description
Users need to search across policies, learning content, users, and leave requests efficiently.
Relevant part of the codebase: Create backend/app/routers/search.py
Expected outcome:
- Integrate Elasticsearch or use SQLite FTS5
- Unified search endpoint that searches across multiple resources
- Highlight search terms in results
- Add filters (date range, department, status)
- Search suggestions/autocomplete
- Frontend search UI with filters