feat(ingestion): harden OFF ingestion for bulk seeding

- Add retry/backoff (429 + 5xx, Retry-After aware) to the OFF adapter so
  transient API errors no longer abort a run.
- Clamp bounded text fields (serving_size, net_content_unit,
  country_of_origin) to their column widths in transform; long OFF values
  previously raised StringDataRightTruncation and rolled back the batch.
- Load each record inside a savepoint (load_record_safe) so one malformed
  source record is skipped instead of aborting the whole import; jobs now
  report an errored count.
- Tests for retry behaviour, serving_size clamping, and per-record isolation.

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

ingestion/tests/test_transform.py

@@ -65,3 +65,14 @@ def test_transform_full_record():
 
 def test_transform_drops_unnamed():
     assert transform({"code": "0000000000000"}) is None
+
+
+def test_transform_clamps_long_serving_size():
+    raw = {
+        "code": "3017624010701",
+        "product_name": "X",
+        "serving_size": "1 portion (30 g) / 1 portion (30 g) / extra long descriptive text here",
+    }
+    rec = transform(raw)
+    assert rec is not None
+    assert len(rec["food"]["serving_size"]) == 32