docker build . stamps the git tag or short commit, not dev (closes #154)

script/build writes the version script/version prints into
dist/package.json, which quak --version reports: the VERSION environment
variable or build arg when one is given, otherwise git describe --tags
--always, otherwise package.json's version. A checkout with .git whose
version comes out empty, dev or unknown fails the build.

.dockerignore no longer leaves out .git, and ARG VERSION has no default,
so a plain docker build . of a clone stamps its commit. script/docker and
script/cibuild still pass the host's version. make build-bin bundles the
built dist/, so the single binary reports the same version.

Model: opus-5-5

script/cibuild

@@ -15,9 +15,9 @@ main() {
     cd "$ROOT"
     # Own line: a failing command substitution inside an argument does
     # not trip `set -e`, so the inline form degrades silently to an
-    # empty constant. VERSION is computed here because .dockerignore
-    # excludes .git, so `git describe` in a build stage yields an empty
-    # version without failing.
+    # empty constant. The version resolved here goes in as the VERSION
+    # build arg, which takes precedence over what the build would derive
+    # from the .git in its context.
     version="$(git describe --tags --always --dirty 2>/dev/null || true)"
     [ -n "$version" ] || version="unknown"
     docker build --no-cache \