Add LLMGraphBuilderService that extracts entities/relationships
from text chunks using Groq instead of Zep Cloud API. Graph data
is persisted to disk as graph_data.json, with fallback to Zep
for existing graphs.
- Updated README.md to reflect the removal of the project creation endpoint, adjusting the workflow steps accordingly.
- Removed the `create_project` function from graph.py, streamlining the project management API by eliminating deprecated functionality.
