fix(docker): merge-time fixes for Update-Codeman.sh (#465)

- Remove exactly the codeman-node-modules/codeman-dist volumes by Compose
  label after a plain `down`, instead of `down --volumes` (which also takes
  any volume an override file declares while the message named two).
  `down --volumes` remains only as a warned fallback when the project name
  cannot be resolved.
- Report a failing first `docker compose config --format json` call with a
  clear error instead of exiting silently under `set -e`.
- Filter empty label lines in the collision guard so an unlabelled container
  cannot hide a real collision; name the moved-checkout exit in its error.
- Comments no longer cite a guard or incident in Start-Codeman.sh that does
  not exist; the README states the real gap (a Node base-image bump leaves
  codeman-node-modules stale because the lockfile did not move).
- docs: Update-Codeman.sh in the docker-self-update.md short-version table
  and a mention in docker-compose.md; "Major updates" moved under "Updating"
  in docker/README.md.
- test: smoke test covers the new sequence, the config failure and the
  empty-line case; quiet stdio; @fileoverview names the fourth concern.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

docs/docker-compose.md

@@ -69,7 +69,7 @@ If that directory was created by an earlier root-running image, change its owner
 
 Codeman updates itself from **App Settings → Updates**, as it does on a bare host. The checkout mounted at `/opt/codeman` is the same directory Compose builds from, so the update's `git checkout` and rebuild land on the host and survive container recreation; the restart is the server exiting, which `restart: unless-stopped` turns into a relaunch on the new build.
 
-That applies application code only. A release that changes `docker/server.Dockerfile`, `docker/docker-compose.yaml`, or adds a key to `docker/.env.example` needs the image rebuilt or the container recreated, which a container cannot do to itself. The updater detects each case and refuses with a message naming what changed; run `docker/Start-Codeman.sh` on the host to apply those.
+That applies application code only. A release that changes `docker/server.Dockerfile`, `docker/docker-compose.yaml`, or adds a key to `docker/.env.example` needs the image rebuilt or the container recreated, which a container cannot do to itself. The updater detects each case and refuses with a message naming what changed; run `docker/Start-Codeman.sh` on the host to apply those. For a major update, or a base-image change `Start-Codeman.sh` does not fully pick up, `docker/Update-Codeman.sh` rebuilds with no layer cache and clears the two build-artefact volumes before handing off to it (see "Major updates" in `docker/README.md`).
 
 `CODEMAN_REPO_PATH` overrides which checkout is mounted. It defaults to the compose project's parent directory, so it normally needs no setting. Point it at a directory that is not a git checkout and in-app updates are reported as unavailable.
 

docs/docker-self-update.md

@@ -10,15 +10,18 @@ this file covers only what the container changes.
 
 ## The short version
 
-| Change in the release            | Applied by                                       |
-| -------------------------------- | ------------------------------------------------ |
-| Application code                 | The in-app updater                               |
-| `docker/server.Dockerfile`       | `docker/Start-Codeman.sh` on the host            |
-| `docker/docker-compose.yaml`     | `docker/Start-Codeman.sh` on the host            |
-| New key in `docker/.env.example` | Add it to `docker/.env`, then `Start-Codeman.sh` |
+| Change in the release                     | Applied by                                                                      |
+| ----------------------------------------- | ------------------------------------------------------------------------------- |
+| Application code                          | The in-app updater                                                              |
+| `docker/server.Dockerfile`                | `docker/Start-Codeman.sh` on the host                                           |
+| `docker/docker-compose.yaml`              | `docker/Start-Codeman.sh` on the host                                           |
+| New key in `docker/.env.example`          | Add it to `docker/.env`, then `Start-Codeman.sh`                                |
+| A major update, or a Node base-image bump | `docker/Update-Codeman.sh` on the host (no-cache rebuild + fresh build volumes) |
 
-The in-app updater detects all three of the bottom rows itself and refuses with a
+The in-app updater detects the three middle rows itself and refuses with a
 message naming what changed, so you never have to work out which case you are in.
+`Update-Codeman.sh` is the heavier option for when `Start-Codeman.sh` is not
+enough: see "Major updates" in `docker/README.md`.
 
 ## Why the container needs its own path
 
@@ -224,9 +227,10 @@ the host and the in-app path works from then on.
 
 **Resetting the build artefacts** — `docker compose down -v`, then
 `Start-Codeman.sh`. This discards the named volumes and re-seeds them from a fresh
-image. `docker/Update-Codeman.sh` scripts exactly this by default (plus an
+image. `docker/Update-Codeman.sh` scripts the same reset by default for the two
+build-artefact volumes (`codeman-node-modules`, `codeman-dist`) only, plus an
 unconditional `--no-cache` rebuild, which a plain `Start-Codeman.sh` run does not
-force on its own) — see "Major updates" in `docker/README.md`.
+force on its own. See "Major updates" in `docker/README.md`.
 
 ## Disabling it