ALL-1872 PR-2: Frontend - bulk-upload results Download button

Add a Download Results button to the bulk upload UI. Two touch points: 1. JobStatusCard — a Download Results button shown when job is COMPLETED or in any terminal state. 2. JobHistoryTable — an action column with a Download Results icon/link per row. Both should trigger GET /v1/bulk-upload/jobs/:jobId/download (PR-1, #12348) and prompt a browser file download. This depends on PR-1 (wilbo/all-1872-bulk-upload-download, #12348) being merged first. Linear: https://linear.app/texture/issue/ALL-1872