Add docker-entrypoint.sh to retry DB connection on startup

The app container starts before DNS resolution is ready,
causing prisma db push to fail. Entrypoint now retries
until the database is reachable.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docker-entrypoint.sh

@@ -0,0 +1,11 @@
+#!/bin/sh
+set -e
+
+echo "Waiting for database..."
+until npx prisma db push --skip-generate 2>/dev/null; do
+  echo "Database not ready, retrying in 3s..."
+  sleep 3
+done
+
+echo "Database schema synced. Starting server..."
+exec node server.js