fix(mosaic): prevent init prompt code execution

packages/mosaic/framework/tools/_scripts/test-mosaic-init-rce.sh

@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Source only the prompt helpers; executing mosaic-init itself requires templates.
+source <(head -n 144 "$(dirname "$0")/mosaic-init")
+
+rm -f /tmp/pwned
+payload='literal "$(touch /tmp/pwned)"'
+AGENT_NAME=""
+prompt_if_empty AGENT_NAME "Agent name" <<<"$payload"
+
+[[ "$AGENT_NAME" == "$payload" ]] || {
+  echo "FAIL: prompt answer did not round-trip literally" >&2
+  exit 1
+}
+[[ ! -e /tmp/pwned ]] || {
+  echo "FAIL: prompt answer executed code" >&2
+  rm -f /tmp/pwned
+  exit 1
+}
+echo "mosaic-init RCE regression: PASS"