feat: expose compact_tables option for markdown export

[kristianQh]

Description:
docling-core's export_to_markdown and save_as_markdown already support
a compact_tables parameter that removes column padding from markdown tables,
but there is currently no way to pass it through docling-jobkit's pipeline.

This PR adds a compact_tables field to ConvertDocumentsOptions and threads
it through all export code paths:

• _export_document_as_content (InBodyTarget / single-doc path)
• _export_documents_as_files (multi-doc / zip path)
• ResultsProcessor.process_documents (S3/target processor path)
• CLI entry points (local.py, multiproc.py)
• KFP pipeline (docling_s3in_s3out.py)

Defaults to False, no behavior change for existing users.

[github-actions]

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[mergify]

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• title ~= ^(fix|feat|docs|style|refactor|perf|test|build|ci|chore|revert)(?:\(.+\))?(!)?:

[dolfim-ibm]

Let's name the argument consistently as md_compact_tables

[dolfim-ibm]

@kristianQh thanks for the contribution. Please see the feedback above about renaming the argument.

Then please also sign off your commits as described in CONTRIBUTING.md. You can also apply a remediation commit as posted in the comment above.