fix(db): use int for netspeed_active to prevent overflow

GetZoneStatsData and GetZoneStatsV2's netspeed_active values can
exceed 2 billion, causing 32-bit integer overflow. Changed from
int32/uint32 to int (64-bit on modern systems) to handle large
network speed totals.

- Update sqlc column overrides to use int type
- Fix type compatibility in dnsanswers.go zoneTotals map
- Regenerate database code with new types

Fixes https://community.ntppool.org/t/error-message-displayed-on-the-monitoring-score-page/4063

ntpdb/models.go

@@ -339,5 +339,5 @@ type ZoneServerCount struct {
 	Date            time.Time                 `db:"date" json:"date"`
 	CountActive     uint32                    `db:"count_active" json:"count_active"`
 	CountRegistered uint32                    `db:"count_registered" json:"count_registered"`
-	NetspeedActive  uint32                    `db:"netspeed_active" json:"netspeed_active"`
+	NetspeedActive  int                       `db:"netspeed_active" json:"netspeed_active"`
 }