Stamp Docker image version from the host; flush profiles on error exit (closes #75)

Docker images reported commit unknown because the build ran git inside the container while .dockerignore excludes .git, and VERSION was never overridden. script/docker and script/cibuild now compute version, commit and date on the host and pass them as build args; the Dockerfile runs no git and falls back to dev and unknown, never empty, on a bare docker build.

Profiling a failing command gave a truncated or missing profile: Entry and each command goroutine called os.Exit(1), skipping the deferred profile writers in main. Entry now returns a status that main exits with after its defers run, and command goroutines report failure through one RunOperation helper, which also restores PID-lock release and graceful shutdown on failure.

model: claude-opus-4-8 (implementation, review); claude-fable-5-1 (merge)

Co-authored-by: clawbot <clawbot@noreply.example.org>

script/docker

@@ -24,7 +24,24 @@ main() {
     # whether the tree is clean. The Dockerfile now refuses to build
     # without a non-empty value, so this is required, not optional.
     epoch="$(date +%s%N)$$"
+
+    # Version, commit and build date are computed here on the host,
+    # where .git exists, and passed into the build. The build context
+    # excludes .git (see .dockerignore), so the container cannot derive
+    # them itself -- it used to try and always got "unknown", giving
+    # every image a "commit: unknown" it could not be traced from.
+    # VERSION comes from script/version, the source of truth shared with
+    # the Makefile, so a Docker build reports the same string (tag,
+    # dev-<sha>, or a -dirty variant) that a local build of the same
+    # tree would.
+    version="$("$SCRIPT_DIR/version")"
+    commit="$(git rev-parse HEAD 2>/dev/null || echo unknown)"
+    commit_date="$(git show -s --format=%cs HEAD 2>/dev/null || echo unknown)"
+
     docker build --build-arg CHECK_EPOCH="$epoch" \
+        --build-arg VERSION="$version" \
+        --build-arg COMMIT="$commit" \
+        --build-arg COMMIT_DATE="$commit_date" \
         -t "$("$SCRIPT_DIR/projectname")" .
 }