fix: address code review findings

internal/cache/store.go

@@ -167,6 +167,11 @@ func GetSearchKey(from, to, date string) *CacheKey {
 	return &CacheKey{Kind: "search", From: from, To: to, Date: date}
 }
 
+// GetSearchKeyWithFarTerm returns the cache key for a search query with far-term flag.
+func GetSearchKeyWithFarTerm(from, to, date, farTermFlag string) *CacheKey {
+	return &CacheKey{Kind: "search", From: from, To: to, Date: date, Request: farTermFlag}
+}
+
 // CacheAside represents the cache-aside pattern implementation.
 // It follows the pattern: Redis → miss → Postgres/API → write-back to Redis.
 type CacheAside struct {