Add explanatory comments to all test scripts

tests/test_shell.sh

@@ -4,8 +4,10 @@ set -euo pipefail
 pass=0
 fail=0
 
+# Allow overriding shellcheck options via env var (e.g. -s bash)
 EXTRA_SHELLCHECK_OPTS="${SHELLCHECK_OPTS:-}"
 
+# Run shellcheck on a Go template after stripping template tags
 shellcheck_tmpl() {
     local tmpl=$1
     # Strip Go template tags ({{ ... }} and {{- ... -}}) into whitespace
@@ -28,10 +30,12 @@ shellcheck_tmpl() {
 }
 
 echo "=== ShellCheck ==="
+# Lint each template file passed as argument
 for f in "$@"; do
     [ -f "$f" ] && shellcheck_tmpl "$f"
 done
 
 echo "---"
 echo "Passed: $pass  Failed: $fail"
+# Exit with failure if any template failed shellcheck
 [ "$fail" -eq 0 ]