Switched the booterm runtime + proddeps stages from node:20-alpine (musl)
to node:20-bookworm-slim (glibc) so host-installed glibc binaries (Claude
Code, opencode, nvm node) run inside the container when invoked from the
terminal pane. node-pty's native .node has to be compiled in the same
libc env as the runtime, so both stages flip together; the TypeScript-only
builder stage stays on alpine.
su-exec is alpine-only; Debian replacement is gosu — swapped in both the
runtime apt install and the tmux default-command. uid/gid 1000 collision
with the bookworm `node` user handled via userdel/groupdel before
groupadd/useradd.
