Ops: add helper script to gate checks on postgres container readiness

Author: sushildalavi

scripts/wait_for_healthy.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+cd "$(dirname "$0")/.."
+
+for i in {1..30}; do
+  status=$(docker compose ps --format json 2>/dev/null | tr -d '\n' || true)
+  if echo "$status" | grep -q '"Service":"postgres"' && echo "$status" | grep -q '"State":"running"'; then
+    echo "postgres container is running"
+    exit 0
+  fi
+  sleep 1
+done
+
+echo "timed out waiting for postgres container"
+exit 1