test(integration): address round-7 review — keep RAG assertion live, fix races

- test_no_results_for_unrelated_query: replace pytest.skip with `unrelated =
  ... or 0.0` and fall through. The physics query almost always returns nothing
  on this corpus, so the skip meant the comparison (and the manual-is-indexed
  check) never ran. Treating no-results as score 0.0 keeps the test live and
  vacuously satisfies `0.0 <= relevant`.
- test_sampling: the three limit/threshold/max-tokens tests now gate on a
  representative created note being searchable (search_term + note_id) instead
  of a bare idle signal that can fire before the new notes are enqueued.
- _get_with_retry: only sleep between attempts, not before giving up.
- _search_helpers: log the id/doc_type schema-drift mismatch at WARNING (CI runs
  --log-cli-level=WARN) so it surfaces instead of hiding behind a timeout.

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

tests/integration/_search_helpers.py

@@ -49,9 +49,10 @@ async def document_is_searchable(
             if r.get("id") == note_id:
                 if r.get("doc_type") == "note":
                     return True
-                # id matched but not a note — surface possible schema drift
-                # rather than silently timing out.
-                logger.debug(
+                # id matched but not a note — surface possible schema drift at
+                # WARNING (CI runs --log-cli-level=WARN) instead of letting the
+                # caller time out with a generic message.
+                logger.warning(
                     "search hit id=%s has doc_type=%s (expected note)",
                     note_id,
                     r.get("doc_type"),