The typed upload helper CallUpload[T] had no caller anywhere — only its
JSON counterpart Call[T] was exercised (by TestCmdRuntime_CallAPI_UnwrapsData)
— so the incremental dead-code gate flagged it as newly unreachable.
Add TestCmdRuntime_CallUpload_PropagatesError, mirroring the Call[T]
coverage: it drives CallUpload through the unsafe --file reject path and
asserts the validation error propagates and T stays zero. This keeps the
provider-facing typed pair (Call[T] / CallUpload[T]) symmetric — both entry
points are now tested rather than only the JSON one — and makes the helper
reachable so the gate passes.
ac2a38cd1b