- @discordjs/opus@0.10.0 has no node>=22 prebuilt, so node-gyp falls back
to source compile and needs python3/make/g++. Add them to apt-get install
in the bookworm-slim base. Verified `docker build` succeeds end-to-end.
- .env.example: rewrite DEV description to cover both behaviors
(clientReady guild-only registration + Prod-commands guild-wipe-then-global).