Update proposed changes on a Draft amendment

Only Draft filings can be changed. Omitted fields are preserved; null clears a proposal. A revision invalidates the previous signature. Invoiced and submitted filings are read-only. Standard keys act on every entity the key owner actively represents. Agent Keys are limited to entities incorporated through the API and need active representation and the listed agent:entity.filing.* scope. Agent writes also require an active Manifestation of Will. OAuth tokens and Partner Keys cannot call these filing endpoints. See https://docs.eprospera.com/entity-filings for signing, payment, and recovery. Agent scope: agent:entity.filing.create.

Account deactivation revokes personal API keys, including Agent Keys, and OAuth authorizations. Account reactivation requires new API keys, including new Agent Keys, and consent; previously issued credentials remain invalid.