updated docs, removed testing files, fixed logging

Invoke-PersonaEngine.ps1

@@ -34,7 +34,8 @@
     run against any new configuration.
 
 .PARAMETER OutputPath
-    Overrides logging.path for this run.
+    Overrides logging.path for this run. When neither this nor logging.path is set,
+    audit records are written to '<current-directory>/logs/persona-engine-audit.ndjson'.
 
 .PARAMETER CorrelationId
     Run identifier. Generated when absent. Appears on every audit record (NFR-005).
@@ -152,7 +153,13 @@ try {
     $context = New-PersonaAuditContext -RunId $runId -EngineVersion $engineVersion -Configuration $config -Mode $mode
 
     $destination = $config.Logging.destination ? [string]$config.Logging.destination : 'stream'
-    $logPath = $OutputPath ? $OutputPath : [string]$config.Logging.path
+
+    # No -OutputPath and no logging.path means "just log somewhere sane" rather than
+    # "log nowhere" - an operator running a plain -WhatIf shouldn't have to configure
+    # a file path just to see what the engine would have done.
+    $configuredPath = [string]$config.Logging.path
+    $defaultLogPath = Join-Path (Get-Location).Path 'logs' 'persona-engine-audit.ndjson'
+    $logPath = $OutputPath ? $OutputPath : ($configuredPath ? $configuredPath : $defaultLogPath)
     $auditParams = @{ Destination = $destination; Path = $logPath; State = $sinkState }
 
     # Tracing is enabled by -Debug or by configuration, and requires acknowledgement