fix: convert Finnhub market cap from millions to absolute USD

Finnhub profile2 reports marketCapitalization in millions; storing it
as dollars made mega-caps like SPCX show as micro (e.g. 1.8M). Normalize
on ingest, add unit tests, and include a one-shot SQL backfill script.

app/providers/fundamentals_chain.py

@@ -101,7 +101,10 @@ class FinnhubFundamentalProvider:
         earnings_payload = earnings_resp.json() if earnings_resp.text else []
 
         metrics = metric_payload.get("metric", {}) if isinstance(metric_payload, dict) else {}
-        market_cap = _safe_float((profile_payload or {}).get("marketCapitalization"))
+        # Finnhub profile2 marketCapitalization is in millions of USD.
+        # Normalize to absolute dollars so cap bands / formatters match FMP & Alpha Vantage.
+        market_cap_millions = _safe_float((profile_payload or {}).get("marketCapitalization"))
+        market_cap = market_cap_millions * 1_000_000.0 if market_cap_millions is not None else None
         pe_ratio = _safe_float(metrics.get("peTTM") or metrics.get("peNormalizedAnnual"))
         revenue_growth = _safe_float(metrics.get("revenueGrowthTTMYoy") or metrics.get("revenueGrowth5Y"))