refactor: 条目记录的工厂搬进模块（manifest 的 schema 有了唯一落点）

New-ItemRecord 是纯工厂：我先用正则扫过它读了哪些外部状态 —— 一处都没有，输入全在参数里，只有一个 Get-Date。所以这是"有状态核心"里唯一可以零判断搬走的一块。

搬走并改名 New-BakNRetItemRecord，同时补上字段说明：这个有序哈希就是 manifest 每个条目的 schema。它原先藏在 Backup.ps1 里，于是"manifest 条目长什么样"这件事只有一个隐式落点；恢复端与工具脚本读的也是同一份 schema，改字段时漏掉某一侧的风险就出在这里。

新增一条断言把这个 schema 钉住：26 个字段的名字与**顺序**逐项比对（顺序是 manifest diff 可读性的前提），另外断言 attemptedAt 每次现取 —— 后者是"把它误写成模块加载时的常量"这种错唯一能被发现的地方。

验收：test.ps1 9/9 全绿（7 与 5.1）、104 个文件两版解析零错、真实清单只读冒烟 4/4。Backup.ps1 从 920 行降到 889 行。

Backup.ps1

@@ -182,37 +182,6 @@ if ($freeSpaceGB -ge 0) {
 }
 
 
-function New-ItemRecord {
-    param([string]$BaseName, [string]$Source, [string]$ResolvedSource, [string]$Phase)
-    return [ordered]@{
-        baseName        = $BaseName
-        source          = $Source
-        resolvedSource  = $ResolvedSource
-        roots           = @()
-        layouts         = @()
-        catalog         = $null
-        archive         = $null
-        action          = $null
-        reason          = $null
-        phase           = $Phase
-        attemptedAt     = (Get-Date).ToString('o')
-        finishedAt      = $null
-        durationSec     = $null
-        exitCode        = $null
-        verified        = $false
-        warnings        = $false
-        attemptWarnings = $false
-        encrypted       = $false
-        security        = $null
-        sourceFiles     = $null
-        sourceBytes     = $null
-        archiveBytes    = $null
-        sha256          = $null
-        lastSuccessAt   = $null
-        successCount    = 0
-        failCount       = 0
-    }
-}
 
 function Save-ItemRecord {
     param($Record, [string]$Action, [string]$Reason, [bool]$ArchiveWarnings = $false)
@@ -523,7 +492,7 @@ foreach ($line in $lines) {
     $resolved = Resolve-BakNRetBackupEntry -Entry $item -CatalogPath $catalogPath
 
     if (-not $resolved.BaseName) {
-        $record = New-ItemRecord -BaseName ('raw:' + $displayPath) -Source $displayPath -ResolvedSource $displayPath -Phase 'parse'
+        $record = New-BakNRetItemRecord -BaseName ('raw:' + $displayPath) -Source $displayPath -ResolvedSource $displayPath -Phase 'parse'
         Save-ItemRecord -Record $record -Action 'failed' -Reason '无法生成归档名' | Out-Null
         $failed++; $failures += $displayPath
         continue
@@ -543,7 +512,7 @@ foreach ($line in $lines) {
     if ($seenBaseNames.ContainsKey($baseName)) {
         $reason = "归档名 '$baseName' 与清单中的 '$($seenBaseNames[$baseName])' 重复（由 '$displayPath' 生成），两者会互相覆盖"
         Write-BakNRetLog "失败: $displayPath，$reason" -Level ERROR
-        $record = New-ItemRecord -BaseName $baseName -Source $displayPath -ResolvedSource $sourcePath -Phase 'backup'
+        $record = New-BakNRetItemRecord -BaseName $baseName -Source $displayPath -ResolvedSource $sourcePath -Phase 'backup'
         Save-ItemRecord -Record $record -Action 'failed' -Reason $reason | Out-Null
         $failed++; $failures += $displayPath
         continue
@@ -555,7 +524,7 @@ foreach ($line in $lines) {
         continue
     }
 
-    $record = New-ItemRecord -BaseName $baseName -Source $displayPath -ResolvedSource $sourcePath -Phase 'backup'
+    $record = New-BakNRetItemRecord -BaseName $baseName -Source $displayPath -ResolvedSource $sourcePath -Phase 'backup'
     $record.archive = $baseName + $tool.Extension
     if ($resolved.CatalogEntry) { $record.catalog = $resolved.CatalogEntry.Path }
     $finalPath = Join-Path $BackupDir $record.archive