fix(reward): add REFERRAL_SERVICE_URL and AUTHORIZATION_SERVICE_URL

reward-service was trying to connect to localhost instead of Docker
network service names, causing connection refused errors.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/services/docker-compose.yml

@@ -311,6 +311,9 @@ services:
       - KAFKA_BROKERS=kafka:29092
       - KAFKA_CLIENT_ID=reward-service
       - KAFKA_GROUP_ID=reward-service-group
+      # External Service URLs
+      - REFERRAL_SERVICE_URL=http://rwa-referral-service:3004
+      - AUTHORIZATION_SERVICE_URL=http://rwa-authorization-service:3009
     depends_on:
       postgres:
         condition: service_healthy
@@ -318,6 +321,10 @@ services:
         condition: service_healthy
       kafka:
         condition: service_started
+      referral-service:
+        condition: service_healthy
+      authorization-service:
+        condition: service_healthy
     healthcheck:
       test: ["CMD", "curl", "-f", "http://localhost:3005/api/v1/health"]
       interval: 30s