feat: package MyAgent as Shirobot plugin

scripts/package-plugin.ps1

@@ -0,0 +1,40 @@
+$ErrorActionPreference = 'Stop'
+
+$projectRoot = [IO.Path]::GetFullPath((Join-Path $PSScriptRoot '..'))
+$artifactRoot = [IO.Path]::GetFullPath((Join-Path $projectRoot 'artifacts'))
+$staging = [IO.Path]::GetFullPath((Join-Path $artifactRoot 'staging'))
+$output = [IO.Path]::GetFullPath((Join-Path $artifactRoot 'plugin'))
+
+foreach ($path in @($artifactRoot, $staging, $output)) {
+    if (-not $path.StartsWith($projectRoot + [IO.Path]::DirectorySeparatorChar, [StringComparison]::OrdinalIgnoreCase)) {
+        throw "Refusing to use path outside project: $path"
+    }
+}
+
+Push-Location (Join-Path $projectRoot 'MyAgent\MyAgent.Web')
+try {
+    npm ci
+    if ($LASTEXITCODE -ne 0) { throw 'npm ci failed' }
+    npm run build
+    if ($LASTEXITCODE -ne 0) { throw 'frontend build failed' }
+}
+finally { Pop-Location }
+
+if (Test-Path -LiteralPath $staging) { Remove-Item -LiteralPath $staging -Recurse -Force }
+if (Test-Path -LiteralPath $output) { Remove-Item -LiteralPath $output -Recurse -Force }
+New-Item -ItemType Directory -Path $staging -Force | Out-Null
+New-Item -ItemType Directory -Path $output -Force | Out-Null
+
+dotnet publish (Join-Path $projectRoot 'Shirobot.Plugin.MyAgent.csproj') -c Release -o $staging
+if ($LASTEXITCODE -ne 0) { throw 'plugin publish failed' }
+
+$files = @('MyAgent.dll', 'Shirobot.Plugin.MyAgent.dll', 'Shirobot.Plugin.MyAgent.deps.json', 'HtmlAgilityPack.dll')
+$files += Get-ChildItem -LiteralPath $staging -Filter 'UglyToad.PdfPig*.dll' -File | Select-Object -ExpandProperty Name
+foreach ($file in $files) {
+    $from = Join-Path $staging $file
+    if (-not (Test-Path -LiteralPath $from)) { throw "Missing publish file: $file" }
+    Copy-Item -LiteralPath $from -Destination (Join-Path $output $file)
+}
+Copy-Item -LiteralPath (Join-Path $staging 'wwwroot') -Destination (Join-Path $output 'wwwroot') -Recurse
+
+Write-Host "Plugin package ready: $output"