Replace corepack-prepared pnpm with `npm install -g pnpm@9.12.0` so the
binary lives in /usr/local/bin (readable by any UID) instead of root's
corepack cache. Avoids re-downloading pnpm on every container restart
when running as a non-root host user.
Also populate .env.development with real dev credentials (Postgres at
192.168.0.210/wabot, dev Telegram bot, operator Telegram ID 818380985).
