feat(document_loaders): add SupadataLoader integration

[MUDASSIR-75]

Description

This PR adds a new SupadataLoader to langchain_community.document_loaders that integrates with the Supadata Web & Video Data API.

Key points:

• New SupadataLoader dataclass in libs/community/langchain_community/document_loaders/supadata.py.
• Supports two operations:
  • operation="transcript" – fetches media transcripts with options:
    • lang (preferred language)
    • text (plain text vs structured)
    • mode ("native" | "auto" | "generate")
  • operation="metadata" – fetches structured media metadata.
• API key handling:
  • Accepts api_key argument, or falls back to the SUPADATA_API_KEY environment variable.
• Runtime dependency on supadata is optional:
  • The loader imports the Supadata SDK lazily inside _get_client.
  • A clear ImportError is raised with an install hint if supadata is not installed.
• Returns Document objects with:
  • page_content as transcript text or JSON-serialized metadata.
  • metadata including source, supadata_operation, and optional lang / mode.
• For long-running transcripts, handles job-based responses by returning a Document with an empty page_content and a job_id stored in metadata.

Tests:

• Adds libs/community/tests/unit_tests/document_loaders/test_supadata_loader.py.
• Tests patch the Supadata client and do not hit the real Supadata API.
• Verified that:
  • metadata operation calls Supadata.metadata with the expected URL and params.
  • transcript operation handles immediate transcript results (with content).
  • transcript operation handles job-style results (with job_id).
  • API key resolution prefers explicit api_key over SUPADATA_API_KEY.

Issue

N/A – this is a new integration; not linked to an existing issue.

Dependencies

• No new hard dependencies added to pyproject.toml.
• At runtime, users must install the official Supadata SDK:
  • pip install supadata
• Unit tests use a patched supadata module and do not require the real service.

Testing

From the libs/community directory:

cd libs/community/tests/unit_tests/document_loaders
uv run pytest test_supadata_loader.py

[MUDASSIR-75]

Hi @mdrxy , could you please help approve the workflows for this PR? Thank you!

[MUDASSIR-75]

Hi @ccurme,

I submitted this PR, adding a SupadataLoader integration. All tests have passed, but the workflows are awaiting maintainer approval to run.

Could you please:

1. Approve the workflows so they can run
2. Review the PR when you have a chance

This PR adds a new document loader for the Supadata Web & Video Data API with full tests and documentation.

Thank you!