Documents the decision to use workdir_parent + identical host<->container
path instead of the overlay2 MergedDir sync that was in the initial fix.
Captures the alternatives (nsenter sync, image-baked configs, path mismatch)
and the operational consequences (prereq directory, out-of-band compose.yaml).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
