docs: add Bourse model provider

[Maurenz2530]

Adds the Bourse OpenAI-compatible provider page under the existing More Providers documentation section, based on issue #13277. Commit: 80bf910. Note: local Mintlify build is blocked by an existing tar ESM incompatibility under Node 24; git diff validation passed.

[github-actions]

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[Maurenz2530]

I have read the CLA Document and I hereby sign the CLA

[RunBourse]

Thank you for writing this - I opened #13277 and did not expect someone to do the page for me.

I am on the Bourse side, so treat me as a reviewer for accuracy rather than a maintainer. Two things worth checking in the page:

• The live catalogue and prices are at https://bourse.run - the table there renders the current listings. Please do not link https://bourse.run/pricing for prices, it is a hub of per-provider links and carries no numbers.
• • Please avoid wording that promises a specific model stays available. Our supply is resold unused provider capacity, so the catalogue changes. Something like "models currently listed" is accurate and will not go stale.
    Happy to answer anything a reviewer raises here, same day.