feat: Agent采集uptime, 后端持久化kernel/uptime/diskIO, 前端磁盘BPS+IOPS展示

- Agent: system.go 添加 readUptime(), SystemStat 携带 Uptime
- Backend: Server 模型新增 Kernel 字段, ReceiveReport 持久化 kernel+uptime
- Backend: /agent/latest 返回 kernel/uptime/port_info/disk_io_info/disk_total
- Frontend: 磁盘监控改为 BPS+IOPS (4张卡片), 系统信息修复内核/运行时长/监听端口/磁盘容量
- 图表单位从 MB/s 改为 KB/s, 添加 formatBPS 工具函数

backend/internal/models/agent_task.go

@@ -3,7 +3,6 @@ package models
 import (
 	"time"
 
-	"gorm.io/gorm"
 )
 
 // AgentTask Agent 远程任务 // Logan.Li
@@ -22,11 +21,10 @@ type AgentTask struct {
 	PickedAt    *time.Time     `json:"picked_at"`  // Agent 拉取时间
 	FinishedAt  *time.Time     `json:"finished_at"` // 完成时间
 	UpdatedAt   time.Time      `json:"updated_at"`
-	DeletedAt   gorm.DeletedAt `gorm:"index" json:"-"`
 }
 
 func (AgentTask) TableName() string {
-	return "agent_tasks"
+	return "monitor_agent_tasks"
 }
 
 // AgentRule 告警规则（基于 Agent 数据） // Logan.Li
@@ -42,11 +40,10 @@ type AgentRule struct {
 	LastTriggered *time.Time     `json:"last_triggered"`
 	CreatedAt     time.Time      `json:"created_at"`
 	UpdatedAt     time.Time      `json:"updated_at"`
-	DeletedAt     gorm.DeletedAt `gorm:"index" json:"-"`
 }
 
 func (AgentRule) TableName() string {
-	return "agent_rules"
+	return "monitor_agent_rules"
 }
 
 // AgentAlert Agent 告警事件 // Logan.Li
@@ -63,9 +60,8 @@ type AgentAlert struct {
 	ResolvedAt  *time.Time     `json:"resolved_at"`
 	CreatedAt   time.Time      `gorm:"index" json:"created_at"`
 	UpdatedAt   time.Time      `json:"updated_at"`
-	DeletedAt   gorm.DeletedAt `gorm:"index" json:"-"`
 }
 
 func (AgentAlert) TableName() string {
-	return "agent_alerts"
+	return "monitor_agent_alerts"
 }