refactor: use canonical token-to-symbol maps for market lookup

Build canonical spot/future token maps with quote priority, unify cache refresh scheduling, and switch resolver/token tests to map-based token lookups.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

internal/helper/binancex/symbol.go

@@ -51,9 +51,9 @@ func Future2SpotSymbol(sym string) string {
 		}
 	}
 
-	spotSym, ok := binance.Future2SpotSymbolMap[sym]
-	if !ok {
-		return sym
+	token := Symbol2Token(sym)
+	if mapped, ok := binance.FutureToken2SpotTokenMap[token]; ok {
+		token = strings.ToUpper(mapped)
 	}
-	return spotSym
+	return token + "USDT"
 }