Verifying the local-dev stack from the host (`docker compose up -d`
+ `psql ... -c "\du"`, `redis-cli PING`) requires the postgres and
redis client binaries on the developer's machine. They were missing
from the prereqs table, so `apt install postgresql-client` /
`apt install redis-tools` was an implicit step nobody knew to run.
Add both to §2's table, with one-line rationale for each. The
Docker row is also tightened to point at the actual local-dev
stack location (`infra/local/`) instead of the placeholder
"Postgres + Redis containers" wording from before that recipe
existed.
`docker compose exec` remains a viable zero-install alternative
when a developer prefers not to touch their host (mentioned only
informally — the host-install path is the documented one).
Julien Gautier