Module search 

VectorCollection search: multi-segment merging with SQ8 reranking.

The search_with_payload_filter method wires payload bitmap pre-filtering into the search path. When all referenced fields in the predicate are indexed, the bitmap is built and passed to search_with_bitmap_bytes. When any field is un-indexed, the search falls back to the full unfiltered path and lets the caller apply post-filtering — the un-indexed predicate is never silently dropped.