Fix: Add missing text_contents parameter to add_contents method signature

[ron-42]

Summary

The synchronous add_contents method was missing the text_contents parameter in its type signature and docstring, while the async add_contents_async method had it correctly defined. This caused confusion and prevented proper IDE autocomplete and type checking when users tried to use knowledge.add_contents(text_contents=[...]).

Key changes:

• Added text_contents: Optional[List[str]] parameter to the add_contents method overload
• Added topics, reader, and remote_content parameters for consistency with the async version
• Updated the docstring to document all newly added parameters

This fix resolves a GitHub issue where users reported that the parameter "contents" in knowledge.add_contents was incorrect and should be "text_contents".

Type of change

• Bug fix
• New feature
• Breaking change
• Improvement
• Model update
• Other:

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Checklist

• Code complies with style guidelines
• Ran format/validation scripts (./scripts/format.sh and ./scripts/validate.sh)
• Self-review completed
• Documentation updated (comments, docstrings)
• Examples and guides: Relevant cookbook examples have been included or updated (if applicable)
• Tested in clean environment
• Tests added/updated (if applicable)

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Additional Notes

The implementation of add_contents already forwarded all arguments correctly to add_contents_async using *args, **kwargs, so only the type signature and documentation needed updating. No behavior changes were made - this is purely a fix for the public API definition.

Existing cookbook examples in cookbook/knowledge/basic_operations/15_text_content.py already demonstrate correct usage of the text_contents parameter with the async version.

solves #5232