feat: add shared Rust MSIX engine and CLI

Closes #2

src/scripts/Build-EgbimMsixSample.ps1

@@ -0,0 +1,56 @@
+param(
+    [Parameter(Mandatory = $true)][string]$Project,
+    [string]$Cli = (Join-Path $PSScriptRoot '..\target\debug\package-builder.exe'),
+    [switch]$Export,
+    [switch]$SignDevelopment
+)
+$ErrorActionPreference = 'Stop'
+$projectPath = (Resolve-Path -LiteralPath $Project).Path
+$cliPath = (Resolve-Path -LiteralPath $Cli).Path
+$sampleRoot = Split-Path -Parent $projectPath
+$reports = Join-Path $sampleRoot 'reports'
+if (-not (Test-Path -LiteralPath $reports)) { New-Item -ItemType Directory -Path $reports | Out-Null }
+$utf8 = New-Object System.Text.UTF8Encoding($false)
+
+function Invoke-BuilderJson([string[]]$BuilderArguments, [string]$ReportPath) {
+    $result = & $cliPath @BuilderArguments
+    $code = $LASTEXITCODE
+    $json = $result -join "`n"
+    [System.IO.File]::WriteAllText($ReportPath, $json, $utf8)
+    if ($code -ne 0) { throw "package-builder failed ($code); report: $ReportPath" }
+    return ($json | ConvertFrom-Json)
+}
+
+# Use the existing Rust engine for planning, packaging, unpack verification and export.
+# Packaging stays in the Rust engine. Optional signing is a separate post-build step.
+$plan = Invoke-BuilderJson -BuilderArguments @('plan','release','--project',$projectPath,'--target','msix-direct') -ReportPath (Join-Path $reports 'plan.json')
+Write-Output "Plan: $($plan.id); files: $($plan.files.Count)"
+$mappingPath = Join-Path $reports 'file-mapping.json'
+if (Test-Path -LiteralPath $mappingPath) {
+    $expected = Get-Content -LiteralPath $mappingPath -Raw -Encoding UTF8 | ConvertFrom-Json
+    $actualTargets = @{}
+    foreach ($file in $plan.files) { $actualTargets[$file.target] = $file }
+    foreach ($file in $expected) {
+        if (-not $actualTargets.ContainsKey($file.target)) { throw "ISM target missing from actual plan: $($file.target)" }
+        $actual = $actualTargets[$file.target]
+        # Compare normalized source paths too; filename matching alone is insufficient.
+        $actualSource = $actual.source -replace '^\\\\\?\\', ''
+        if ($actualSource -ine $file.preparedSource -or [uint64]$actual.bytes -ne [uint64]$file.bytes -or $actual.sha256 -ne $file.sha256) {
+            throw "ISM source/size mismatch: $($file.ismFileId)"
+        }
+    }
+    if ($plan.files.Count -ne ($expected.Count + 2)) { throw 'Unexpected payload count; expected ISM files plus two logo assets.' }
+}
+$result = Invoke-BuilderJson -BuilderArguments @('build','--project',$projectPath,'--plan-id',$plan.id) -ReportPath (Join-Path $reports 'build-result.json')
+Write-Output "Build: $($result.status); signing: $($result.signing)"
+Write-Output "Artifact: $($result.artifact)"
+if ($SignDevelopment) {
+    & (Join-Path $PSScriptRoot 'Sign-DevelopmentMsix.ps1') `
+        -Release (Join-Path $sampleRoot ("releases\" + $result.buildId + '\release.json')) `
+        -Output (Join-Path $sampleRoot ('signed-development-' + $result.buildId))
+}
+if ($Export) {
+    $exportRoot = Join-Path $sampleRoot ('export-' + $plan.id)
+    $exportedPath = Invoke-BuilderJson -BuilderArguments @('export','--project',$projectPath,'--release',$plan.id,'--output',$exportRoot) -ReportPath (Join-Path $reports 'export-result.json')
+    Write-Output "Export: $exportedPath"
+}