feat: integrate BERTopic for topic modeling

[Septimus4]

Checklist

• [ ] poetry run pytest passes locally with my changes
• [ ] Tests have been added or updated to cover the changes
• [ ] Documentation has been updated as needed
• [ ] Code style checks pass
• [x] Commit messages follow the Conventional Commits guidelines

Affected Components

Everything

Description of Changes

Added dependencies for BERTopic, llvmlite, numba, and Neo4j. Implemented incremental topic modeling with BERTopic in main.py, including model initialization, data loading, fitting, saving, and updating topics in Neo4j. Added FastAPI and ConnectRPC

Additional Notes