fix: Extract text content from Message objects for agent input (#10009)

* fix: Extract text content from Message objects for agent input

Previously, when Message objects were passed to agents, they were converted
to LangChain BaseMessage format which caused input to display as
'(content='text' additional_kwargs={} response_metadata={})' instead of
clean text.

This fix properly extracts the content attribute from LangChain messages
to ensure agents receive clean text input.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* [autofix.ci] apply automated fixes

* fix: Improve input handling in LCAgentComponent for message conversion

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Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Edwin Jose <edwin.jose@datastax.com>
Co-authored-by: Gabriel Luiz Freitas Almeida <gabriel@langflow.org>