fix(docker): address maintainer review on #377

Two real bugs the review caught, both verified live against a real
build on the Unraid host:

1. entrypoint.sh's chown fired on ANY ownership mismatch, not just a
   directory the daemon itself created root-owned. A host tree
   legitimately owned by some other account - an existing
   CODEMAN_CASES_PATH the README already allows pointing at a normal
   projects directory, or appdata under a different PUID/PGID
   convention than the one in use - got silently recursively re-owned
   with one log line to explain it. Now gated on the target actually
   being root-owned; anything else is a clean refusal naming the
   directory, its owner, and PUID/PGID. Start-Codeman.sh also now
   pre-creates CODEMAN_CASES_PATH the same way it already did
   CODEMAN_APPDATA_PATH, so Compose never has to materialise a missing
   bind source as root in the first place - the in-container chown
   becomes a safety net, not the primary mechanism.

2. The CLI-update chown (chown -R .../node_modules /usr/local/bin)
   handed the runtime account write access to entrypoint.sh itself
   (root-owned, executed as root on every container start with
   CHOWN/DAC_OVERRIDE/SETUID/SETGID) and the node binary - owning the
   DIRECTORY is enough to rename it aside and drop a replacement, which
   would let a compromised session arrange for its own script to run
   as root at the next restart. The four CLIs now install into a
   dedicated /opt/codeman-cli prefix (NPM_CONFIG_PREFIX); only that
   directory is chowned, /usr/local stays root-owned throughout.

Smaller fixes from the same review:

- Start-Codeman.sh's volume-refresh label filter wasn't project-scoped:
  a second Compose stack on the same host sharing the `codeman-dist`
  volume KEY could have had ITS volume deleted. Added a
  com.docker.compose.project filter, resolved from this stack's own
  `compose config --format json`.
- Override-file precedence was backwards (checked .yaml before .yml;
  Compose actually prefers .yml) - swapped, plus a warning when both
  exist.
- entrypoint.sh's setpriv now also passes --bounding-set -all, so
  CapBnd actually clears post-drop rather than just CapPrm/CapEff.
- A comment on git_head_commit() noting it returns nothing for a
  worktree checkout (.git as a file), consistent with the script's
  existing -d .git convention elsewhere.
- Doc drift: CLAUDE.md's Docker Compose section still described the
  old pre-created-and-chowned-by-hand model and didn't mention the
  root-then-drop entrypoint; the state-files list was missing
  docker-build-source.json; docs/docker-compose.md and
  docker/.env.example still had the pre-rename `Coding/codeman` path
  in one place each.

Verified end to end against a real build on the Unraid host: a
root-owned bind source is corrected as before; a directory owned by
neither root nor PUID:PGID is refused rather than silently rewritten;
a correctly-owned directory is left alone entirely; the four CLIs
resolve via PATH from /opt/codeman-cli while /usr/local/bin,
/usr/local/lib/node_modules and entrypoint.sh itself stay root-owned;
CapBnd is fully cleared post-drop.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01R9ZSTEenc8soSu9bTi8Xru

docker/.env.example

@@ -25,7 +25,7 @@ CODEMAN_APPDATA_PATH=/mnt/user/appdata/codeman
 # start script detects it from the compose file's own location, so it only needs
 # setting for direct `docker compose` use or a checkout kept elsewhere. Point it
 # at a directory that is not a git checkout and in-app updates are unavailable.
-# CODEMAN_REPO_PATH=/mnt/user/appdata/Coding/codeman/app
+# CODEMAN_REPO_PATH=/mnt/user/appdata/codeman/app
 
 # Required for Docker cases. This must be an absolute path on the Docker host.
 # Codeman and each isolated case use this same path, so it cannot be a