wip(assembler): round S5 -- streaming gates + trace; coarse-first order kept opt-in (no win)

Walkable/enclosed/refined gates defined; JSONL trace joins request, worker start,
build/apply and discards. Coarse-first + dynamic near reserve behind
voxel.StreamingCoarseFirst / voxel.StreamingDynamicNearReserve (default 0 =
S4 order): matched runs showed no walkability or full-view win and slower
LOD0/1 refinement. Instruments settled: 3.1 s standalone reproduced (16.7 s was
another generation route); black early captures were clear-only frames.
Hashes equal S4; Core-off, M2, SurfaceWorld/FloatingIslands BuildHost pass.

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

Standalone/Build.ps1

@@ -2,14 +2,14 @@
 param(
     [string]$OutputName = 'VoxelForgeCoreStandalone.exe',
     [ValidateSet('All','Core')][string]$Target = 'All',
-    [ValidateRange(1,16)][int]$CompileWorkers = 16,
+    [ValidateRange(1,12)][int]$CompileWorkers = 12,
     [ValidateSet('Normal','BelowNormal')][string]$BuildPriority = 'Normal'
 )
 
 $ErrorActionPreference = 'Stop'
 $BuildHostProcess = Get-Process -Id $PID
 $BuildHostProcess.PriorityClass = $BuildPriority
-$BuildHostProcess.ProcessorAffinity = [IntPtr]0xFFFF
+$BuildHostProcess.ProcessorAffinity = [IntPtr]0xFFF
 $Root = [IO.Path]::GetFullPath($PSScriptRoot)
 $BuildDir = Join-Path $Root 'Build\VoxelForgeCore'
 $BinDir = Join-Path $Root 'bin'
@@ -24,6 +24,33 @@ $CoreLibrary = Join-Path $BuildDir 'VoxelForgeCore.lib'
 $VcVars = 'E:\Program Files\Microsoft Visual Studio\2022\Community\VC\Auxiliary\Build\vcvars64.bat'
 if (-not (Test-Path -LiteralPath $VcVars -PathType Leaf)) { throw "MSVC environment script not found: $VcVars" }
 
+if (-not ('VoxelForgeStandaloneBuildMemoryProbe' -as [type])) {
+    Add-Type -TypeDefinition @'
+using System;
+using System.Runtime.InteropServices;
+public static class VoxelForgeStandaloneBuildMemoryProbe {
+    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
+    private struct MEMORYSTATUSEX {
+        public uint dwLength, dwMemoryLoad;
+        public ulong ullTotalPhys, ullAvailPhys, ullTotalPageFile, ullAvailPageFile;
+        public ulong ullTotalVirtual, ullAvailVirtual, ullAvailExtendedVirtual;
+    }
+    [DllImport("kernel32.dll", SetLastError = true)]
+    private static extern bool GlobalMemoryStatusEx(ref MEMORYSTATUSEX status);
+    public static ulong AvailablePhysicalBytes() {
+        var status = new MEMORYSTATUSEX();
+        status.dwLength = (uint)Marshal.SizeOf(typeof(MEMORYSTATUSEX));
+        if (!GlobalMemoryStatusEx(ref status)) throw new InvalidOperationException("GlobalMemoryStatusEx failed.");
+        return status.ullAvailPhys;
+    }
+}
+'@
+}
+while ([VoxelForgeStandaloneBuildMemoryProbe]::AvailablePhysicalBytes() -lt 4GB) {
+    Write-Warning 'Standalone build is waiting for at least 4 GiB of free physical memory.'
+    Start-Sleep -Seconds 20
+}
+
 $SourceManifest = Join-Path $Root 'Core\core_sources.txt'
 if (-not (Test-Path -LiteralPath $SourceManifest -PathType Leaf)) { throw "Core source manifest not found: $SourceManifest" }
 $CoreSourceNames = @(Get-Content -LiteralPath $SourceManifest | ForEach-Object { $_.Trim() } |