Update README for lexical fallback flow

Use lexical fallback for abbreviation typos

Use offline hashing embeddings by default

Make embedding index rebuild configurable

Initial CASE-IN assistant prototype

create: test_embedding_model.py, README.md, init.sql, docker-compose.yml, requirements.txt, sample_queries.md, index.html, embedding_client.py, gigachat_client.py, load_qdrant.py, pipeline.py, dictionary.py, schemas.py, main.py, config.py, __init__.py