Add IPv4 range optimization for IP to AS lookups

- Add v4_ip_start and v4_ip_end columns to live_routes table
- Calculate IPv4 CIDR ranges as 32-bit integers for fast lookups
- Update PrefixHandler to populate IPv4 range fields
- Add GetASInfoForIP method with optimized IPv4 queries
- Add comprehensive tests for IP conversion functions

internal/database/utils.go

@@ -10,11 +10,6 @@ func generateUUID() uuid.UUID {
 	return uuid.New()
 }
 
-const (
-	ipVersionV4 = 4
-	ipVersionV6 = 6
-)
-
 // detectIPVersion determines if a prefix is IPv4 (returns 4) or IPv6 (returns 6)
 func detectIPVersion(prefix string) int {
 	if strings.Contains(prefix, ":") {