chore(ci): guards against tracked build artefacts

scripts/check-repo-hygiene.sh

@@ -0,0 +1,25 @@
+#!/usr/bin/env sh
+set -eu
+
+failed=0
+
+tracked_build_outputs="$(git ls-files | grep -E '(^|/)([Bb]in|[Oo]bj)(/|\\)' || true)"
+if [ -n "$tracked_build_outputs" ]; then
+  printf '%s\n' "Tracked build output paths found:" >&2
+  printf '%s\n' "$tracked_build_outputs" >&2
+  failed=1
+fi
+
+tracked_backslash_paths="$(git ls-files | grep '\\' || true)"
+if [ -n "$tracked_backslash_paths" ]; then
+  printf '%s\n' "Tracked paths containing literal backslashes found:" >&2
+  printf '%s\n' "$tracked_backslash_paths" >&2
+  failed=1
+fi
+
+if [ "$failed" -ne 0 ]; then
+  printf '%s\n' "Remove generated files from Git before building." >&2
+  exit 1
+fi
+
+printf '%s\n' "Repository hygiene check passed."