Reference seller modules do not compile against the in-repo adcp/v3 module #597

Surfaced by @torbenbrodt in his 2026-10-25 review of #554: reference/hello-seller and reference/seller-agent pin the released adcp/v3 v3.0.0 because they do not compile against the in-repo v3 module (e.g. ProductAllowedAction removal, PackageInput.Budget pointer change on the 3.3-dev line).

Consequence: the reference resolvers/handlers are never exercised against the tree they ship with — combined-behavior tests against the updated SDK have to live in the SDK packages instead (see TestRegisteredAccountLifecycle in #554), and drift between the reference code and the in-repo SDK is only caught when someone patches the pins locally.

Worth deciding: track the in-repo module via a replace directive in CI, pin to a newer release, or document the pin as deliberate with a compile check against the tree.