docs: add Spidra integration (provider, tools, document loader)

[Shittu olumide (zenUnicorn)]

Adds documentation for the langchain-spidra integration package (published on PyPI at https://pypi.org/project/langchain-spidra/).

Changes

New pages

• src/oss/python/integrations/providers/spidra.mdx — Provider overview page
• src/oss/python/integrations/tools/spidra.mdx — Tools guide (SpidraScrape, SpidraCrawl, SpidraBatchScrape)
• src/oss/python/integrations/document_loaders/spidra.mdx — Document loader guide (SpidraLoader)

Updated index pages

• providers/all_providers.mdx — Added Spidra card
• tools/index.mdx — Added Spidra to the Web browsing table and all-tools grid
• document_loaders/index.mdx — Added SpidraLoader to the Webpages table

Package info

• PyPI: https://pypi.org/project/langchain-spidra/
• GitHub: https://github.com/spidra-io/spidra-langchain
• This PR is documentation only; the package lives in its own repo.

[github-actions]

Thanks for opening a docs PR, Shittu olumide (@zenUnicorn)! When it's ready for review, please add the relevant reviewers:

• @mdrxy (Python integrations)

[langchain-oss-automated-triage]

Thanks for contributing a new integration docs page, Shittu olumide (@zenUnicorn)!

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