Please address the comments from this code review:

## Overall Comments
- The build cache statistics added to `go_build` rely on `go build -v` line counts and a fixed `/tmp/go-build-compiled-count` file, which can be both inaccurate (non-1:1 with compiled units) and racy if multiple builds run in parallel; consider using a unique temp file per invocation and/or gating this logging behind a flag or env var.
- The `git ls-files | xargs touch` step in the composite action mutates mtimes for every tracked file, which could interfere with incremental build tooling or other languages in the same job; consider narrowing this to Go source/test files or to the directories actually used by Go.

## Individual Comments

### Comment 1
<location path="scripts/go-tool.sh" line_range="108" />
<code_context>
-  invoke_go_build -o "$output" "${dirs[@]}"
+  local total
+  total=$(go list -deps "${dirs[@]}" 2>/dev/null | wc -l | tr -d ' ')
+  local compiled_count=/tmp/go-build-compiled-count
+  invoke_go_build -o "$output" "${dirs[@]}" 2> >(tee >(wc -l | tr -d ' ' > "$compiled_count") >&2)
+  wait
</code_context>
<issue_to_address>
**issue (bug_risk):** Use a per-process or per-invocation temp file instead of a fixed path for compiled_count

A fixed `/tmp` path means concurrent runs of this script (or multiple `go_build` calls in one job) will race on the same `compiled_count` file, causing corrupted or incorrect counts. Please use a unique temp file per invocation (e.g., via `mktemp` or including `$$`/`$BASHPID` and job name in the filename) and clean it up afterward.
</issue_to_address>

### Comment 2
<location path="scripts/go-tool.sh" line_range="112-115" />
<code_context>
+  invoke_go_build -o "$output" "${dirs[@]}" 2> >(tee >(wc -l | tr -d ' ' > "$compiled_count") >&2)
+  wait
+  local compiled
+  compiled=$(cat "$compiled_count" 2>/dev/null | tr -d ' ')
+  local cached=$((total - compiled))
+  echo >&2 "Build cache: ${cached}/${total} deps cached ($compiled compiled)"
+  if [[ "$total" -gt 0 ]] && [[ $((cached * 100 / total)) -lt 50 ]]; then
+    echo >&2 "WARNING: Build cache hit rate below 50% (${cached}/${total}). Significant code changes invalidate the cached build — expect slower compilation."
+  fi
</code_context>
<issue_to_address>
**issue (bug_risk):** Harden arithmetic against empty or non-numeric totals/compiled counts

If `go list` or the build step fails (or their output format changes), `total`/`compiled` can be empty or non-numeric. Then `cached=$((total - compiled))` and the percentage calculation will throw a bash arithmetic error and abort. Please default missing values to 0 and ensure both vars are integers (e.g. `${total:-0}`, `${compiled:-0}` with a simple regex check), or skip the cache-reporting logic when the counts aren’t valid.
</issue_to_address>