refactor code and improve daily cache handling of deleted VMs

internal/tasks/inventorySnapshots.go

@@ -23,31 +23,6 @@ import (
 	"github.com/vmware/govmomi/vim25/types"
 )
 
-type InventorySnapshotRow struct {
-	InventoryId     sql.NullInt64
-	Name            string
-	Vcenter         string
-	VmId            sql.NullString
-	EventKey        sql.NullString
-	CloudId         sql.NullString
-	CreationTime    sql.NullInt64
-	DeletionTime    sql.NullInt64
-	ResourcePool    sql.NullString
-	Datacenter      sql.NullString
-	Cluster         sql.NullString
-	Folder          sql.NullString
-	ProvisionedDisk sql.NullFloat64
-	VcpuCount       sql.NullInt64
-	RamGB           sql.NullInt64
-	IsTemplate      string
-	PoweredOn       string
-	SrmPlaceholder  string
-	VmUuid          sql.NullString
-	SnapshotTime    int64
-}
-
-type snapshotTotals = db.SnapshotTotals
-
 // RunVcenterSnapshotHourly records hourly inventory snapshots into a daily table.
 func (c *CronTask) RunVcenterSnapshotHourly(ctx context.Context, logger *slog.Logger) (err error) {
 	jobCtx := ctx
@@ -442,11 +417,6 @@ func filterRecordsInRange(records []report.SnapshotRecord, start, end time.Time)
 	return filtered
 }
 
-type columnDef struct {
-	Name string
-	Type string
-}
-
 var summaryUnionColumns = []string{
 	`"InventoryId"`, `"Name"`, `"Vcenter"`, `"VmId"`, `"EventKey"`, `"CloudId"`, `"CreationTime"`,
 	`"DeletionTime"`, `"ResourcePool"`, `"Datacenter"`, `"Cluster"`, `"Folder"`,