Fix artifact upload path: place release manifest inside packages directory

The multi-path upload caused nested directory structure on download.
Move ReleaseManifestFile into PackagesDirectory so all release artifacts
share a single upload path.

Made-with: Cursor

Author: Hongwei-MB

.github/workflows/ci.yml

@@ -175,9 +175,7 @@ jobs:
         uses: actions/upload-artifact@v7
         with:
           name: packages
-          path: |
-            artifacts/packages/**
-            artifacts/release-manifest.json
+          path: artifacts/packages/**
           if-no-files-found: error
 
       - name: Upload app artifacts

build/BuildTask.Parameters.cs

@@ -39,7 +39,7 @@ partial class BuildTask
     AbsolutePath PackagesDirectory => ArtifactsDirectory / "packages";
     AbsolutePath PublishDirectory => ArtifactsDirectory / "publish";
 
-    AbsolutePath ReleaseManifestFile => ArtifactsDirectory / "release-manifest.json";
+    AbsolutePath ReleaseManifestFile => PackagesDirectory / "release-manifest.json";
     AbsolutePath BuildOutputsMarkerFile => ArtifactsDirectory / ".build-outputs" / "build-outputs.json";
     AbsolutePath ToolManifestFile => RootDirectory / ".config" / "dotnet-tools.json";
     AbsolutePath DirectoryBuildPropsFile => RootDirectory / "Directory.Build.props";