[test] add examples-check target with stubbed BIN and no-network validation for example scripts

scripts/bin_stub.sh

@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+# Lightweight stub for examples-check: simulates the PolyScribe CLI without I/O or network
+# - Accepts any arguments
+# - Exits 0
+# - Produces no output unless VERBOSE_STUB=1
+# - Never performs network operations
+# - Never reads from stdin
+set -euo pipefail
+
+if [[ "${VERBOSE_STUB:-0}" == "1" ]]; then
+  echo "[stub] polyscribe $*" 1>&2
+fi
+
+# Behave quietly if -q/--quiet is present by default (no output)
+# Honor --help/-h: print minimal usage if verbose requested
+if [[ "${VERBOSE_STUB:-0}" == "1" ]]; then
+  for arg in "$@"; do
+    if [[ "$arg" == "-h" || "$arg" == "--help" ]]; then
+      echo "PolyScribe stub: no-op (examples-check)" 1>&2
+      break
+    fi
+  done
+fi
+
+# Always succeed quietly
+exit 0