/news: normalize rounded-zero score so "-0.00" renders as "+0.00"

A balanced feed (XAU and USD means nearly cancelling) yields a tiny
negative net that "+.2f" rendered as "-0.00" — seen live 2026-08-03.
Regression test uses that day's actual per-currency means (300 tests).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017975c1TufZ3xRYAq8iWTCS

test_all.py

@@ -1898,6 +1898,17 @@ def _():
     assert "Bearish" in text
 
 
+@test("_news_text never renders negative zero")
+def _():
+    # Balanced feed: XAU and USD means nearly cancel → net -0.0035,
+    # which "+.2f" would render as "-0.00" without normalization.
+    ctx = FundamentalContext(news_sentiment={"XAU": 0.0238, "USD": 0.0273})
+    text = _news_text(ctx, NewsEngine(PlatformConfig().news))
+    assert "-0.00" not in text
+    assert "+0.00" in text
+    assert "Neutral" in text
+
+
 @test("_news_text degrades on empty context")
 def _():
     text = _news_text(FundamentalContext(), NewsEngine(PlatformConfig().news))