feat(snmp,ui): устройства за портом (MAC/IP) в таблице 2

Добавил сбор FDB/ARP по SNMP (BRIDGE-MIB + ipNetToMedia), хранение и API /port-devices.
В UI Таблица 2 теперь показывает MAC/IP за выбранным портом после клика по строке Таблицы 1.

Made-with: Cursor

internal/scans/postgres_store.go

@@ -538,3 +538,49 @@ func (s *PostgresStore) PurgeAllScanData() error {
 	_, err := s.db.ExecContext(context.Background(), `truncate table scan_jobs restart identity cascade`)
 	return err
 }
+
+func (s *PostgresStore) SavePortDeviceResult(scanID string, result PortDeviceResult) error {
+	query := `
+insert into scan_port_devices (scan_id, ip, if_index, mac, learned_ip, checked_at)
+values ($1, $2, $3, $4, $5, $6)`
+	_, err := s.db.ExecContext(
+		context.Background(),
+		query,
+		scanID,
+		result.IP,
+		result.IfIndex,
+		result.MAC,
+		result.LearnedIP,
+		result.CheckedAt,
+	)
+	return err
+}
+
+func (s *PostgresStore) ListPortDeviceResults(scanID string, filterIP string, filterIfIndex int, limit int) []PortDeviceResult {
+	if limit <= 0 {
+		limit = 20000
+	}
+	query := `
+select ip::text, if_index, coalesce(mac, ''), coalesce(learned_ip::text, ''), checked_at
+from scan_port_devices
+where scan_id = $1
+  and ($2 = '' or ip = $2::inet)
+  and ($3 = 0 or if_index = $3)
+order by if_index asc, mac asc, learned_ip asc
+limit $4`
+	rows, err := s.db.QueryContext(context.Background(), query, scanID, filterIP, filterIfIndex, limit)
+	if err != nil {
+		return nil
+	}
+	defer rows.Close()
+
+	out := make([]PortDeviceResult, 0, 256)
+	for rows.Next() {
+		var r PortDeviceResult
+		if err = rows.Scan(&r.IP, &r.IfIndex, &r.MAC, &r.LearnedIP, &r.CheckedAt); err != nil {
+			return nil
+		}
+		out = append(out, r)
+	}
+	return out
+}