Upload Marketing Collateral

Upload marketing collateral files.

Creates Files + FileVersions + MarketingCollateral rows atomically.

Every file must carry a collateral type, matching the Figma and Google endpoints. An untyped asset has no channel, and a rule with an explicit collateral_types scope never applies to one, so every standard is enforced against it at once.

vendor_id selects which company on the marketing page the collateral belongs to — the self company, a partner, or a fintech prospect are screenable. Defaults to the self vendor.