Replace 6-table JOIN with 3-step approach:
1. get_llmage_llm() for base info (llm + llm_api_map + llmcatelog)
2. Cached uapi lookup (ioid, stream, callbackurl)
3. Cached uapiio lookup (input_fields)
Benefits:
- Code reuse: eliminates duplicate SQL
- Performance: uapi/uapiio cached with 5min TTL
- Maintainability: separate concerns for model info vs API config
- Adds invalidate_uapi_cache() for config changes