test(M00): add landmark-region visual diff

tools/sweep_render_checkpoint_camera_pose.ps1

@@ -12,6 +12,7 @@ param(
     [double[]]$CameraFovValues = @(),
     [int]$ViewportWidth = 1280,
     [int]$ViewportHeight = 900,
+    [int[]]$ComparisonRegion = @(),
     [double]$WaitSeconds = 8.0,
     [double]$MeasureSeconds = 0.1,
     [switch]$PlanOnly
@@ -33,6 +34,9 @@ if (-not (Test-Path -LiteralPath $GodotPath)) {
 if (-not (Test-Path -LiteralPath $ReferenceDirectory)) {
     throw "Reference directory not found: $ReferenceDirectory"
 }
+if ($ComparisonRegion.Count -notin @(0, 4)) {
+    throw "ComparisonRegion requires x,y,width,height"
+}
 
 $invariantCulture = [Globalization.CultureInfo]::InvariantCulture
 $isJointFovSweep = $CameraFovValues.Count -gt 0
@@ -89,6 +93,9 @@ try {
                 "--reference", $ReferenceDirectory, "--candidate", $candidateOutput,
                 "--only", $Checkpoint, "--output", $comparisonReport
             )
+            if ($ComparisonRegion.Count -eq 4) {
+                $comparisonArguments += @("--region", ($ComparisonRegion -join ","))
+            }
             $comparisonProcess = Start-Process -FilePath $GodotPath -ArgumentList $comparisonArguments -Wait -PassThru -NoNewWindow
             if ($comparisonProcess.ExitCode -notin @(0, 1)) {
                 throw "Comparison failed for yaw=$yawText pitch=$pitchText"
@@ -131,6 +138,7 @@ try {
         viewport = @($ViewportWidth, $ViewportHeight)
         wait_seconds = $WaitSeconds
         measure_seconds = $MeasureSeconds
+        comparison_region = @($ComparisonRegion)
         candidates = $rankedCandidates
     }
     New-Item -ItemType Directory -Force -Path $absoluteOutput | Out-Null