Introducing cascading retrieval: Unifying dense and sparse with reranking

What this post added

Introduced sparse-only vector index type (in early access), the pinecone-sparse-english-v0 sparse embedding model with whole-word tokenization and model-free queries, and integrated reranking capabilities (cohere-rerank-3.5, pinecone-rerank-v0). These features enable cascading retrieval pipelines combining dense, sparse, and reranking.