fix(identity-service): 移除 db push 回退，只用 migrate deploy

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

backend/services/identity-service/Dockerfile

@@ -56,7 +56,7 @@ COPY --from=builder /app/dist ./dist
 RUN echo '#!/bin/sh\n\
 set -e\n\
 echo "Running database migrations..."\n\
-npx prisma migrate deploy || npx prisma db push --accept-data-loss\n\
+npx prisma migrate deploy\n\
 echo "Starting application..."\n\
 exec node dist/src/main.js\n' > /app/start.sh && chmod +x /app/start.sh