wip(assembler): round S1 -- one Core voxel-size source; per-tile feature lists (islands)

AVoxelWorld::CoreVoxelSizeCm (default 25, 32 voxels/tile) flows through plan, field,
mesher, content, water, atmosphere, edits and collision. Staged-owner BuildHost passes at
20 cm (SurfaceWorld + islands, W1/W8/W16, anchors, BP edits, collision) with a fixed-25cm
negative control; default-size hashes match round 4; Core off stays legacy 12.5 cm.
Reusable BuildWorldAssemblyFeatureTileListV1; wired into FloatingIslands only so far.
256-island stress: tile p95 112.5 -> 2.0 ms, 0 mismatches, dropped-feature control fails.
Content placement measured (no populated cells): island ground search 7.25 ms/cell vs
legacy 0.29 ms -- open. Outside-review evaluation in Round5/REPORT.md.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MmSoF64BbRFmk9C3p1VsBJ

Tools/BuildVoxelForgeCoreHost.ps1

@@ -1,6 +1,6 @@
 [CmdletBinding()]
 param(
-    [ValidateRange(1, 4)][int]$MaxParallelActions = 4,
+    [ValidateRange(1, 16)][int]$MaxParallelActions = 16,
     [ValidateRange(60, 900)][int]$TimeoutSeconds = 900
 )
 
@@ -166,7 +166,7 @@ $buildSucceeded = $false
 for ($attempt = 1; $attempt -le 2 -and -not $buildSucceeded; ++$attempt) {
     $attemptStdout = if ($attempt -eq 1) { $BuildStdout } else { Join-Path $LogRoot 'UBT-CoreIntegration.retry.stdout.log' }
     $attemptStderr = if ($attempt -eq 1) { $BuildStderr } else { Join-Path $LogRoot 'UBT-CoreIntegration.retry.stderr.log' }
-    Write-Host "BuildHost UBT attempt $attempt of 2; max parallel actions=$MaxParallelActions; BelowNormal priority."
+    Write-Host "BuildHost UBT attempt $attempt of 2; max parallel actions=$MaxParallelActions; Normal priority."
     Wait-ForLaunchMemory
     $foreignEditors = @(Get-Process -ErrorAction SilentlyContinue |
         Where-Object { $_.ProcessName -like 'UnrealEditor*' })
@@ -177,7 +177,7 @@ for ($attempt = 1; $attempt -le 2 -and -not $buildSucceeded; ++$attempt) {
     $process = Start-Process -FilePath $dotnet -ArgumentList $argumentList -WorkingDirectory $PluginRoot `
         -RedirectStandardOutput $attemptStdout -RedirectStandardError $attemptStderr `
         -WindowStyle Hidden -PassThru
-    $process.PriorityClass = [Diagnostics.ProcessPriorityClass]::BelowNormal
+    $process.PriorityClass = [Diagnostics.ProcessPriorityClass]::Normal
     $started = [datetime]::UtcNow
     while (-not $process.HasExited) {
         Start-Sleep -Seconds 5