CHW-4407 BillyPolicyInvalid

Billy policy payload was missing or malformed; supply a decodable policy draft

Default message: Billy policy payload was missing or malformed; supply a decodable policy draft
HTTP status: 400 (client)

Problem. /api/billy/approve-policy (or the action-proposal JSON decode) failed. Cause. The body could not be decoded into the policy / action proposal struct. Fix. Send a body that matches the policy.Policy / billy.ActionProposal schema. HTTP 400.