Fix AS detail view to show unique prefixes

- Update GetASDetails query to GROUP BY prefix instead of using DISTINCT
- Use MAX(last_updated) to get the most recent update time for each prefix
- This prevents duplicate prefixes from appearing when announced by multiple peers
- Maintains the same prefix count and ordering

internal/database/database.go

@@ -767,11 +767,12 @@ func (d *Database) GetASDetails(asn int) (*ASN, []LiveRoute, error) {
 	asnInfo.Handle = handle.String
 	asnInfo.Description = description.String
 
-	// Get prefixes announced by this AS
+	// Get prefixes announced by this AS (unique prefixes with most recent update)
 	query := `
-		SELECT DISTINCT prefix, mask_length, ip_version, last_updated
+		SELECT prefix, mask_length, ip_version, MAX(last_updated) as last_updated
 		FROM live_routes
 		WHERE origin_asn = ?
+		GROUP BY prefix, mask_length, ip_version
 		ORDER BY ip_version, mask_length, prefix
 	`