test(#7548): expect archived=None for a missing sidecar

The sidecar default is now 'no opinion' (None) so the projection can fall
back to state.db's archived flag. Update the #4842 perf test's missing-
sidecar expectation to match.

Co-authored-by: webtecnica <webtecnica@users.noreply.github.com>

tests/test_issue4842_cron_projection_perf.py

@@ -199,7 +199,9 @@ def test_missing_sidecar_returns_default_without_caching_growth(tmp_path):
     session_dir.mkdir()
     with mock.patch("api.models.SESSION_DIR", session_dir):
         meta = models._state_projection_sidecar_metadata("cron_nope_999")
-    assert meta == {"title": None, "archived": False}
+    # No sidecar means no opinion on archived (None), so the projection falls back
+    # to the state.db row's archived flag (#7548) instead of forcing it to False.
+    assert meta == {"title": None, "archived": None}
     # No file → nothing cached (so the cache can't be poisoned by absent files).
     assert len(models._SIDECAR_METADATA_CACHE) == 0