Address user confusion from "pending" jobs with no explanation:
* FileRef.display_name — optional UI-only metadata so the UI can show
the client-provided upload filename instead of the on-disk UUID. The
pipeline ignores it for execution; older stored rows stay valid
because the field is optional.
* jobs_repo.queue_position — returns (ahead, total_active) so the
fragment can render "Queue position: N ahead" for pending jobs and
"About to start" when N == 0. Terminal jobs return (0, 0).
* Fragment polish — status / queue / elapsed / result panels; live dot
via CSS animation; CPU-mode details block when /healthz reports
ocr_gpu: false. Elapsed time formats as MM:SS (running or finished).
* /healthz gains an additive ocr_gpu key (true/false/null). Existing
postgres/ollama/ocr gating is unchanged. Surya records CUDA availability
on warm_up; FakeOCRClient has no attribute and probes to None.
* Persistent header with "Upload a new extraction" link and copy-to-
clipboard button for the current job id; <title> includes job id.
Tests: +7 unit + +6 integration. Full suite 321 green (272 unit, 49
integration). Lint clean.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
