Implement streamdown plugin `ReadDocxFile` for `ReadFile`

[gravity-api]

Create a streamdown plugin ReadDocxFile that extracts text from .docx files. This plugin is executed via the ReadFile meta plugin when FileFormat=Docx.

Inputs

Name	Type	Mandatory	Description
Path	String	Expression	❌
Url	String	Expression	❌
Base64	String	Expression	❌

Outputs (for meta normalization)

Output Key	Description
Text	Extracted text
ParagraphsCount	Optional count of parsed paragraphs

Implementation Notes

• Resolve bytes from source:

  • Base64 → bytes
  • Path → File.ReadAllBytes
  • Url → HTTP GET bytes

• Parse using OpenXML SDK (DocumentFormat.OpenXml)

• Preserve order; join paragraphs with double newlines for readability.