Get User Data Export

Return the current state of job_id for the authenticated user.

job_id is typed :class:~uuid.UUID so FastAPI answers 422 at the boundary; raw text would instead reach a Postgres uuid comparison and surface as a driver conversion error (HTTP 500).

Args: job_id: UUID of the export job to poll. auth: Authenticated user context.

Returns: The job's lifecycle state plus (when ready) a presigned URL minted on this poll, so a repeated poll never sees a stale signature. Its lifetime is far shorter than the archive's 24h retention — see DOWNLOAD_URL_TTL_SECONDS.

Raises: HTTPException: 404 when job_id is unknown or another user's (collapsed to avoid leaking existence); 500 on failure.