chore: remove splitters and Conversation

docs/04-chat-history.ipynb

docs/examples/conversation-topic-splitter.ipynb

docs/examples/rolling-window-splitter.ipynb

docs/examples/unstructured-element-splitter.ipynb

docs/examples/video-splitter.ipynb

docs/source/route_layer/sync.rst

semantic_router/index/pinecone.py

semantic_router/schema.py

semantic_router/splitters/__init__.py

semantic_router/splitters/base.py

semantic_router/splitters/consecutive_sim.py

semantic_router/splitters/cumulative_sim.py

semantic_router/splitters/rolling_window.py

semantic_router/splitters/utils.py

semantic_router/text.py

tests/unit/test_splitters.py

tests/unit/test_text.py