[Aug 13, 2026] Collateral Type on Lien Filings

Every lien filing now carries a structured collateral_type classification: a closed set of values describing what the filing secures (for example, real property, a motor vehicle, or a tax obligation, with a not applicable value where no collateral grant applies).

The field sits alongside the existing collateral_statement on each filing returned by GET /lien_searches/{id} and is displayed in the Console lien view.

How it is derived: for filing types where the collateral is known from the filing type itself, the classification is assigned deterministically. For the rest, it is classified from the filing's collateral statement, so filings without a machine-readable statement return a null collateral_type.

No integration changes required. collateral_type is an additive, nullable field and existing
integrations are unaffected.