restructure and tweaks

.gitignore

00_performance_tests.ipynb

decision_layer/__init__.py

decision_layer/encoders/__init__.py

pyproject.toml

results1.csv

semantic_router/__init__.py

semantic_router/encoders/__init__.py

semantic_router/encoders/base.py

semantic_router/encoders/cohere.py

semantic_router/encoders/huggingface.py

semantic_router/encoders/openai.py

semantic_router/layer.py

semantic_router/schema.py

walkthrough.ipynb