fix: add GEMINI_API_KEY environment variable for zine generation

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

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

docker-compose.yml

@@ -10,6 +10,7 @@ services:
       - NODE_ENV=production
       - HOSTNAME=0.0.0.0
       - PORT=3000
+      - GEMINI_API_KEY=${GEMINI_API_KEY}
     volumes:
       - zine-data:/app/data
     networks: