feat(triage): failed-processing triage — probe errored files, flag defects, recover (#125 C1-C3)

An errored GPU job's stored reason is a suspicion; the file probe is the
verdict. A 15-min beat sweep (triage_gpu_errors) runs verify_integrity's own
probe (sha256 + decode) on each errored image ONCE and writes both verdicts:
ImageRecord.integrity_status and the new GpuJob.triage_status ('defect' |
'file_ok', migration 0072). Every classification logs at WARNING so it
surfaces in Logs/System Activity.

- 'defect' rows are excluded from /retry_errors (re-running a known-bad file
  burns agent time re-minting the tombstone); response now reports
  defects_kept and the GpuAgentCard toast says so.
- GET /api/gpu/errors: triage view — reason buckets (classify_reason),
  probe verdicts, per-job detail. POST /errors/triage runs the sweep now.
- POST /api/gpu/errors/<id>/recover: reuses the Layer-2 refetch pattern —
  delete the defective copy + record (full cascade takes the tombstones too)
  and re-poll its subscription Source so a fresh copy re-imports and re-enters
  the pipeline; 'no_source' when nothing pollable resolves.
- New 'Failed processing' card (GpuTriageCard) in Maintenance: verdict counts,
  reason summary, probe-now, defect list with thumbnails + per-image Recover.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CDgx8bQS5YrGRK76v8HUnM

tests/test_api_gpu.py

@@ -213,3 +213,50 @@ async def test_retry_errors_requeues_only_errored(client, db):
 
     st = await (await client.get("/api/gpu/status")).get_json()
     assert st["pending"] == 1 and st["error"] == 0
+
+
+@pytest.mark.asyncio
+async def test_retry_errors_keeps_triaged_defects(client, db):
+    """A probe-confirmed DEFECT is a bad FILE — requeueing it just burns agent
+    time re-minting the tombstone, so /retry_errors leaves it for the recovery
+    surface and reports it as defects_kept."""
+    img1 = await _img(db, "4" * 64)
+    img2 = await _img(db, "5" * 64)
+    db.add(GpuJob(image_record_id=img1.id, task="ccip", status="error",
+                  attempts=3, error="moov atom not found",
+                  triage_status="defect"))
+    db.add(GpuJob(image_record_id=img2.id, task="ccip", status="error",
+                  attempts=3, error="ffmpeg timed out after 1200s"))
+    await db.commit()
+
+    body = await (await client.post("/api/gpu/retry_errors")).get_json()
+    assert body["requeued"] == 1
+    assert body["defects_kept"] == 1
+
+    rows = dict((await db.execute(
+        select(GpuJob.image_record_id, GpuJob.status)
+    )).all())
+    assert rows[img1.id] == "error"       # defect stays tombstoned
+    assert rows[img2.id] == "pending"     # operational failure requeued
+
+
+@pytest.mark.asyncio
+async def test_errors_endpoint_reports_triage_view(client, db):
+    img = await _img(db, "6" * 64)
+    db.add(GpuJob(image_record_id=img.id, task="ccip", status="error",
+                  attempts=3,
+                  error="no frames sampled from video — moov atom not found"))
+    await db.commit()
+
+    resp = await client.get("/api/gpu/errors")
+    assert resp.status_code == 200
+    body = await resp.get_json()
+    assert body["total"] == 1
+    assert body["by_class"] == {"truncated_or_corrupt": 1}
+    assert body["triage"]["unclassified"] == 1
+    item = body["items"][0]
+    assert item["image_id"] == img.id
+    assert item["task"] == "ccip"
+    assert item["reason_class"] == "truncated_or_corrupt"
+    assert item["triage_status"] is None
+    assert item["image_url"].startswith("/images/")