chore: address review for market filename refactor

Rename pair tests to match post-refactor boundaries and remove unused alpha cache refresh helper.

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

internal/data/market/main.go

@@ -46,15 +46,6 @@ func NewMarketData() *MarketData {
 	return ms
 }
 
-func (ms *MarketData) alphaCacheRefreshLoop() {
-	ms.refreshAlphaTokenCache()
-	ticker := time.NewTicker(time.Hour)
-	defer ticker.Stop()
-	for range ticker.C {
-		ms.refreshAlphaTokenCache()
-	}
-}
-
 func (ms *MarketData) refreshTradingPairCache() error {
 	if err := ms.refreshSpotPairCache(); err != nil {
 		return err