Add fastgpt as seperate assistant mode

engine/providers/llm/__init__.py

@@ -1 +1,14 @@
 """LLM providers."""
+
+from providers.llm.openai import MockLLMService, OpenAILLMService
+
+try:  # pragma: no cover - import depends on optional sibling SDK
+    from providers.llm.fastgpt import FastGPTLLMService
+except Exception:  # pragma: no cover - provider remains lazily available via factory
+    FastGPTLLMService = None  # type: ignore[assignment]
+
+__all__ = [
+    "FastGPTLLMService",
+    "MockLLMService",
+    "OpenAILLMService",
+]