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>

Dockerfile

@@ -35,4 +35,7 @@ RUN mkdir -p /app/uploads
 
 EXPOSE 3000
 
-CMD ["sh", "-c", "npx prisma db push --skip-generate && node server.js"]
+COPY docker-entrypoint.sh ./
+RUN chmod +x docker-entrypoint.sh
+
+CMD ["./docker-entrypoint.sh"]