Major rewrite of the zif_llm_client interface with a new ZCL_LLM_CLIENT as wrapper around the old interface. For backwards compatibilty use the zif_llm_client_int interface.
- Cleanup: Removed AuthType - manual cleanup might be required, delete it from table zllm_providers and structure zllm_provider_disp
- Auto-retry for failed calls (3 times by default, configurable)
- Simple test report zllm_client_example added
- Bugfixes, especially for the Gemini client and tool use