Switch the app image from node:24-alpine to node:24.19.0-bookworm-slim in
both build and runtime stages (Technology-Stack 5.4: glibc Debian base
required because argon2 is a native dependency; musl/Alpine causes
native-module build surprises), and the db image from postgres:16-alpine
to postgres:18-bookworm (Technology-Stack 5.2/5.4/6.2 + golden tuple 7
pin PostgreSQL 18.6; 18-bookworm is the 18.x line on Debian bookworm).
Update tests/compose-config.test.mjs so the committed assertions lock in
the corrected image bases (db image, Dockerfile build/runtime stages,
parser probe).
implementer