feat(patreon): structured ingester results + quarantine surfacing — #704 step 1

The native ingester faked gallery-dl stdout (`Cursor:` lines, summary) and
phase 3 regex-scraped it back — so Patreon run-stats were mostly zero and
quarantine stats blank. We own the ingester, so it now RETURNS structured
data and phase 3 reads it directly.

- DownloadResult gains run_stats/cursor/posts_processed (None/0 on the
  gallery-dl path, which keeps the text route).
- Ingester builds real run_stats from per-media outcome counts, sets the
  checkpoint cursor structurally (no fake `Cursor:` stdout), and counts
  posts processed. download_service phase 3 uses dl_result.run_stats when
  present; the backfill lifecycle + TIMEOUT→PARTIAL block checkpoint
  dl_result.cursor instead of parse_last_cursor(stdout).
- #4 quarantine: PatreonDownloader reports a distinct "quarantined"
  MediaOutcome (with the _quarantine dest); the ingester surfaces a real
  files_quarantined + quarantined_paths + run_stats.quarantined_count
  (was hardcoded 0). Quarantined media isn't written or marked seen.
- Cleanup: parse_last_cursor + _CURSOR_RE (and the now-unused `import re`)
  removed from gallery_dl — the structured cursor replaced the scrape.

Tests: ingester result carries real run_stats/cursor/posts_processed +
quarantine counts; downloader quarantines an invalid file as "quarantined";
backfill cursor tests pass cursor= structurally; dropped the
parse_last_cursor tests.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/test_download_service.py

@@ -59,7 +59,7 @@ def _make_jpg(path: Path, split: str = "h"):
 def _make_fake_dl_result(
     *, success=True, written_paths=None, quarantined_paths=None,
     files_downloaded=0, error_type=None, error_message=None,
-    stdout="", stderr="",
+    stdout="", stderr="", cursor=None, run_stats=None, posts_processed=0,
 ):
     return SimpleNamespace(
         success=success,
@@ -78,6 +78,11 @@ def _make_fake_dl_result(
         duration_seconds=1.23,
         started_at="2026-05-20T14:00:00+00:00",
         completed_at="2026-05-20T14:01:00+00:00",
+        # plan #704: native ingester now returns the cursor + run_stats
+        # structurally (no more stderr `Cursor:` scraping).
+        cursor=cursor,
+        run_stats=run_stats,
+        posts_processed=posts_processed,
     )
 
 
@@ -505,7 +510,7 @@ async def test_backfill_chunk_progress_advances_cursor(
 
     svc, _ = _backfill_svc(db, db_sync, tmp_path, _make_fake_dl_result(
         success=False, written_paths=[], files_downloaded=0,
-        stderr="[patreon][debug] Cursor: 03:PAGE2:xyz\n",
+        cursor="03:PAGE2:xyz",
     ))
     await svc.download_source(source.id)
 
@@ -534,7 +539,7 @@ async def test_backfill_state_running_selects_backfill_mode_and_resumes(
 
     svc, calls = _backfill_svc(db, db_sync, tmp_path, _make_fake_dl_result(
         success=False, written_paths=[],
-        stderr="[patreon][debug] Cursor: 03:RESUME2:next\n",
+        cursor="03:RESUME2:next",
     ))
     await svc.download_source(source.id)
 
@@ -587,7 +592,7 @@ async def test_backfill_cap_exhaustion_stalls(
 
     svc, _ = _backfill_svc(db, db_sync, tmp_path, _make_fake_dl_result(
         success=False, written_paths=[],
-        stderr="[patreon][debug] Cursor: 03:MORE:left\n",
+        cursor="03:MORE:left",
     ))
     await svc.download_source(source.id)
 
@@ -623,7 +628,7 @@ async def test_backfill_stuck_guard_stalls_after_two_no_advance(
         "config_overrides": {"_backfill_state": "running", "_backfill_cursor": "stuck"},
         "backfill_runs_remaining": 5,
     }
-    stuck = _make_fake_dl_result(success=False, stderr="Cursor: stuck\n")
+    stuck = _make_fake_dl_result(success=False, cursor="stuck")
 
     await svc._apply_backfill_lifecycle(ctx, stuck)
     await db.commit()
@@ -661,7 +666,7 @@ async def test_backfill_timeout_chunk_reclassified_to_ok(
         success=False, files_downloaded=3,
         error_type=ErrorType.TIMEOUT,
         error_message="Download timed out",
-        stderr="[patreon][debug] Cursor: 03:NEXT:page\n",
+        cursor="03:NEXT:page",
     ))
     event_id = await svc.download_source(source.id)