add earnings-date guard — warn when a report falls in the target horizon

Finnhub's earnings calendar now supplies next_earnings_date through the
fundamentals chain; persisted on fundamental_data (migration 006) and exposed in
the fundamentals API. The recommendation panel warns when earnings fall within
the ~30-day target horizon (a report can gap price through stop/target) and
otherwise shows the next date. Informational only.

Deploy: run alembic upgrade (new fundamental_data.next_earnings_date column).

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

app/routers/fundamentals.py

@@ -42,6 +42,7 @@ async def read_fundamentals(
             revenue_growth=record.revenue_growth,
             earnings_surprise=record.earnings_surprise,
             market_cap=record.market_cap,
+            next_earnings_date=record.next_earnings_date,
             fetched_at=record.fetched_at,
             unavailable_fields=_parse_unavailable_fields(record.unavailable_fields_json),
         )