Add POSTGRES_DATABASE details to the env file

Editor assessment

Exactly what a chore should look like. The subject names the specific variable — POSTGRES_DATABASE — and the target file, so anyone scanning the log knows both the what and the where without opening the diff. At modest length with imperative 'Add', it needs no body, and none is provided; the Co-authored-by trailer is correctly formatted with the required blank line before it. One could quibble that .env.example changes are developer-facing configuration and thus chore is right while docs or build would be over-reach — here chore is the correct, conventional call. No breaking markers, patch-level maintenance, no changelog impact expected. There is nothing to fix in this message; it is a small, complete, honest unit of history.