Pin audit sink writes against ambient WhatIfPreference

Add-Content/New-Item in Write-PersonaAuditRecord honour ShouldProcess, so
an ambient $WhatIfPreference left set in the caller's session (e.g. from
dot-sourcing a prior -WhatIf run) silently turned the audit write into a
no-op, even though the sink itself never opts into ShouldProcess. The
audit log is supposed to be unconditional under -WhatIf, so both calls
now pin -WhatIf:$false -Confirm:$false.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/Audit/Write-PersonaAuditRecord.ps1

@@ -69,12 +69,20 @@ function Write-PersonaAuditRecord {
 
                 $directory = Split-Path -Parent $Path
                 if ($directory -and -not (Test-Path -LiteralPath $directory)) {
-                    $null = New-Item -ItemType Directory -Path $directory -Force
+                    $null = New-Item -ItemType Directory -Path $directory -Force -WhatIf:$false -Confirm:$false
                 }
 
                 # Append, one record per line. UTF-8 without BOM so the file is
                 # machine-readable by any NDJSON consumer.
-                Add-Content -LiteralPath $Path -Value $line -Encoding utf8NoBOM -ErrorAction Stop
+                #
+                # -WhatIf:$false / -Confirm:$false pin this call regardless of any
+                # ambient $WhatIfPreference in the caller's session (e.g. left set by
+                # dot-sourcing an earlier -WhatIf run). Add-Content honours
+                # ShouldProcess, and this sink is not optional under -WhatIf - the
+                # audit trail is what makes preview mode auditable at all, so it must
+                # write unconditionally, independent of anything the caller's scope
+                # happens to have set.
+                Add-Content -LiteralPath $Path -Value $line -Encoding utf8NoBOM -ErrorAction Stop -WhatIf:$false -Confirm:$false
             }
             catch {
                 if ($null -ne $State -and $State.FileSinkFailed) { return }