internal/rosa: create metadata alongside artifact

This enables deferring evaluation of azalea-based packages and fixes the longstanding quirk of version being disjoint from other metadata.

Signed-off-by: Ophestra <cat@gensokyo.uk>

cmd/mbf/internal/pkgserver/index.go

@@ -33,10 +33,10 @@ type packageIndex struct {
 // metadata holds [rosa.Metadata] extended with additional information.
 type metadata struct {
 	handle rosa.ArtifactH
-	*rosa.Artifact
+	*rosa.Metadata
 
-	// Populated via [rosa.Toolchain.Version], [rosa.Unversioned] is equivalent
-	// to the zero value. Otherwise, the zero value is invalid.
+	// Copied from [rosa.Metadata], [rosa.Unversioned] is equivalent to the zero
+	// value. Otherwise, the zero value is invalid.
 	Version string `json:"version,omitempty"`
 	// Output data size, available if present in report.
 	Size int64 `json:"size,omitempty"`
@@ -61,12 +61,12 @@ func (index *packageIndex) populate(report *rosa.Report) (err error) {
 	index.names = make(map[string]*metadata)
 	ir := pkg.NewIR()
 	for i, handle := range handles {
-		a, version := rosa.Native().Std().MustLoad(handle)
+		meta, a := rosa.Native().Std().MustLoad(handle)
 		m := metadata{
 			handle: handle,
 
-			Artifact: rosa.Native().MustGet(handle),
-			Version:  version,
+			Metadata: meta,
+			Version:  meta.Version,
 		}
 		if m.Version == "" {
 			return errors.New("invalid version from " + m.Name)