Execute a search query with filtering, exclusion, and result boosting against Elasticsearch indices.

This endpoint extends filter-and-sort by adding a boost array for soft relevance tuning. Boost filters act as SHOULD clauses — they increase the relevance score of matching documents without strictly filtering them out.

Filter Logic:

• include array: must-match filters (AND logic), identical to Filter and Sort.
• exclude array: must-not filters (NOT logic), identical to Filter and Sort.
• boost array: SHOULD directives (OR logic) with configurable boost multipliers. A document can match zero or more boost filters; matching multiple boosts stacks their effects.

Boost Values:

• 1.0 = no effect on score
• > 1.0 = increase score (e.g., 2.0 doubles the relevance contribution)
• < 1.0 = decrease score

Sorting Note: The boost endpoint does not support sort_by. Results are ordered by relevance score (highest first), which incorporates both the base Elasticsearch score and any boost multipliers.