Pure functions for search result highlighting and snippet extraction.

This namespace provides functions for highlighting matching terms
in search results and extracting relevant snippets.
All functions are pure (no side effects).

Architecture: Functional Core (Pure)

Pure document construction and filter-key conversion for search.

Key functions:
- defsearch             — bind a SearchDefinition to a var (data only)
- collect-definitions   — the definitions a :wagoe/search component holds
- api-enabled?          — whether the generic search API serves an index
- build-document*       — construct a SearchDocument from field values
- filter-key->json-key  — convert a filter keyword to a snake_case JSON key

What a search asks for, before any store sees it: the sanitized query and
the filter terms. `wagoe.search.shell.query-sql` turns them into SQL.

Pure ranking and scoring functions for search results.

This namespace provides functions for calculating relevance scores,
applying boosts, and normalizing results. All functions are pure.

Architecture: Functional Core (Pure)