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>

frontend/src/pages/TickerDetailPage.tsx

@@ -262,6 +262,7 @@ export default function TickerDetailPage() {
         longSetup={longSetup}
         shortSetup={shortSetup}
         currentPrice={priceInfo?.price}
+        nextEarningsDate={fundamentals.data?.next_earnings_date}
       />
 
       {/* Chart — always visible */}