Evokoa/pggraph — reverse-engineered prompt

Build me an open source Postgres add on that gives normal Postgres tables graph search abilities without making people move their data to a separate graph database. I want users to install it in a test Postgres database, register ordinary tables and their relationships, build a derived graph index from foreign keys, then ask SQL questions like who is connected to this person within two steps, what is the shortest path between two records, and search nodes across the registered tables.

Keep Postgres as the source of truth and make the graph data rebuildable from the tables. Include a Docker quickstart that creates sample tables, installs the extension, builds the graph, and runs example queries. Add a simple playground so people can try preset data and see results. Use Rust for the extension, support modern Postgres versions, and keep it clearly marked as an alpha project for local testing, not production. Look up current Postgres extension docs online if you need to.