fix: update import in __init__.py to use renamed decorator

- Change import from llm_documented to prompt_schema
- Update __all__ list to include the new name

Author: abrichr

pydantic_prompt/__init__.py

@@ -1,4 +1,4 @@
-from pydantic_prompt.core import llm_documented
+from pydantic_prompt.core import prompt_schema
 
-__all__ = ["llm_documented"]
-__version__ = "0.1.0"
+__all__ = ["prompt_schema"]
+__version__ = "0.1.0"