fix: Fix pre-commit issues and update tests

- Fix import sorting and unused imports
- Update type annotations to use built-in types (list, dict) instead of typing.List/Dict
- Fix trailing whitespace and end-of-file issues
- Fix Chinese fullwidth comma to regular comma
- Update test_main_cli.py to test_document_rag.py
- Add backward compatibility test for main_cli_example.py
- Pass all pre-commit hooks (ruff, ruff-format, etc.)

README.md

@@ -195,7 +195,7 @@ python ./examples/document_rag.py --query "What are the main techniques LEANN ex
 --embedding-model MODEL  # e.g., facebook/contriever, text-embedding-3-small
 --embedding-mode MODE    # sentence-transformers, openai, or mlx
 
-# LLM Parameters  
+# LLM Parameters
 --llm TYPE              # openai, ollama, or hf
 --llm-model MODEL       # e.g., gpt-4o, llama3.2:1b
 --top-k N               # Number of results to retrieve (default: 20)