fix: forward sentiment-adjustment fields in the scores API response

get_score computed base_score / sentiment_score / sentiment_adjustment /
max_sentiment_adjustment, but the router's _map_composite_breakdown built the
response model from only the five original keys and silently dropped the rest — so
the API always returned null for them. That's why the ticker page showed neither the
"Composite = Base + Sentiment" caption nor the ± marker on the sentiment row despite
the frontend and scoring service both supporting it. Pass the fields through, with a
guard test so they can't be dropped again.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/routers/scores.py

@@ -39,6 +39,10 @@ def _map_composite_breakdown(raw: dict | None) -> CompositeBreakdownResponse | N
         missing_dimensions=raw["missing_dimensions"],
         renormalized_weights=raw["renormalized_weights"],
         formula=raw["formula"],
+        base_score=raw.get("base_score"),
+        sentiment_score=raw.get("sentiment_score"),
+        sentiment_adjustment=raw.get("sentiment_adjustment"),
+        max_sentiment_adjustment=raw.get("max_sentiment_adjustment"),
     )
 
 router = APIRouter(tags=["scores"])