style: normalise blank lines between definitions

- two between top-level definitions, one between methods, none doubled inside a body

tests/test_news_lookahead.py

@@ -106,7 +106,6 @@ def test_global_news_empty_after_filter_is_informative(monkeypatch):
     assert "unavailable" in out and "not an absence" in out
 
 
-
 def _ticker_with(articles, monkeypatch):
     class FakeTicker:
         def __init__(self, *a, **k):
@@ -162,7 +161,6 @@ def test_coverage_gap_boundaries(dates, expect_gap):
         assert "unavailable for 2026-05-01..2026-05-08" in out and "not an absence" in out
 
 
-
 @pytest.mark.unit
 def test_ticker_news_empty_feed_for_a_past_window_is_unavailable(monkeypatch):
     _ticker_with([], monkeypatch)