feat: init pc-monitor project

- Client: Go-based Windows hardware monitoring (CPU, GPU, memory, disk, network, power)
- Server: Go + Gin + SQLite backend with REST API
- Frontend: Vue 3 + Element Plus dashboard
- Docker deployment support
- Windows service installation script

server/service/alert.go

@@ -0,0 +1,99 @@
+package service
+
+import (
+	"fmt"
+	"pc-monitor-server/model"
+	"pc-monitor-server/repository"
+	"time"
+)
+
+type AlertService struct {
+	alertRepo   *repository.AlertRepository
+	metricsRepo *repository.MetricsRepository
+}
+
+func NewAlertService(alertRepo *repository.AlertRepository, metricsRepo *repository.MetricsRepository) *AlertService {
+	return &AlertService{alertRepo: alertRepo, metricsRepo: metricsRepo}
+}
+
+func (s *AlertService) CreateRule(rule *model.AlertRule) error {
+	rule.CreatedAt = time.Now()
+	return s.alertRepo.CreateRule(rule)
+}
+
+func (s *AlertService) GetRulesByDevice(deviceID string) ([]model.AlertRule, error) {
+	return s.alertRepo.GetRulesByDevice(deviceID)
+}
+
+func (s *AlertService) DeleteRule(id string) error {
+	return s.alertRepo.DeleteRule(id)
+}
+
+func (s *AlertService) GetActiveAlerts() ([]model.Alert, error) {
+	return s.alertRepo.GetActiveAlerts()
+}
+
+func (s *AlertService) ResolveAlert(id string) error {
+	return s.alertRepo.ResolveAlert(id)
+}
+
+func (s *AlertService) CheckAlerts(deviceID string, metrics *model.Metrics) error {
+	rules, err := s.alertRepo.GetRulesByDevice(deviceID)
+	if err != nil {
+		return err
+	}
+
+	for _, rule := range rules {
+		value := getMetricValue(metrics, rule.Metric)
+		if checkThreshold(value, rule.Operator, rule.Threshold) {
+			alert := &model.Alert{
+				ID:        fmt.Sprintf("%s-%s-%d", deviceID, rule.ID, time.Now().Unix()),
+				DeviceID:  deviceID,
+				RuleID:    rule.ID,
+				Metric:    rule.Metric,
+				Value:     value,
+				Message:   fmt.Sprintf("%s %s %.2f (threshold: %.2f)", rule.Metric, rule.Operator, value, rule.Threshold),
+				Status:    "active",
+				CreatedAt: time.Now(),
+			}
+			s.alertRepo.CreateAlert(alert)
+		}
+	}
+	return nil
+}
+
+func getMetricValue(m *model.Metrics, metric string) float64 {
+	switch metric {
+	case "cpu_usage":
+		return m.CPUUsage
+	case "cpu_temperature":
+		return m.CPUTemperature
+	case "memory_usage":
+		return m.MemoryUsage
+	case "gpu_usage":
+		return m.GPUUsage
+	case "gpu_temperature":
+		return m.GPUTemperature
+	case "battery_level":
+		return float64(m.BatteryLevel)
+	default:
+		return 0
+	}
+}
+
+func checkThreshold(value float64, operator string, threshold float64) bool {
+	switch operator {
+	case ">":
+		return value > threshold
+	case ">=":
+		return value >= threshold
+	case "<":
+		return value < threshold
+	case "<=":
+		return value <= threshold
+	case "==":
+		return value == threshold
+	default:
+		return false
+	}
+}