docs: update README, API reference, dev-log, project structure with Agent monitoring + quick-alarm + latest fixes

- README.md: React 19, default pwd 123456, Docker Compose deploy, correct module list
- api-reference.md: add Agent monitoring section (report/latest/rules/quick-setup/alerts/tasks/kline)
- dev-log.md: new entry documenting hostname/IP fix, system collector, offline detection, quick alarm
- project-structure.md: add agent/ directory, dev-log.md link, React 19

backend/internal/api/routes/routes.go

@@ -443,6 +443,7 @@ func Register(r *gin.Engine, db *gorm.DB, log *zap.Logger, cfg *config.Config, c
 
 		// 告警规则
 		agentQuery.GET("/rules", taskHandler.ListRules)
+		agentQuery.POST("/rules/quick-setup", taskHandler.QuickSetupRules)
 		agentQuery.POST("/rules", taskHandler.CreateRule)
 		agentQuery.PUT("/rules/:id", taskHandler.UpdateRule)
 		agentQuery.DELETE("/rules/:id", taskHandler.DeleteRule)