Geospatial RAG on Postgres: One Query for "Where" and "What Kind"

Site selection is two search problems wearing a trenchcoat — where (spatial) and what-kind (semantic). You don't need a vector database next to PostGIS. Here's how to fuse PostGIS proximity and pgvector similarity in a single Postgres query, feed it to an LLM agent, and put it on a map — built and measured on real grid data.