`ProviderDriverError.message` is derived from `detail`, so interpolating
`cause.message` duplicated the underlying failure into the wrapper message
while the cause already carried it. The sibling mapping in this same file
("Failed to build Pi orchestration adapter.") already used the bounded
form, so the two wrappers now match.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>