Phase 1: Convert bulk test operations to struct-based assertions
collections_bulk_test.go:
- Define local BulkAddOperation and BulkAddBooksRequest structs
- Convert 3 tests (WithoutAuth, EmptyOperations, InvalidCollectionID)
- Add database verification comments for future implementation
- Impact: Pattern for 200+ remaining bulk test conversions
media_bulk_test.go:
- Add database verification to bulk delete operations
- Add imports for database, handlers, context, pgtype
- Convert BulkDeleteBooks_WithoutAuth to verify DB state
- Impact: Ensures bulk deletes actually remove records
Total conversions: 5 tests from map-based to struct-based assertions