fix(module): run scripts/fetch-upstream-manifests

sow-module renamed scripts/fetch-hak-manifest.sh to
scripts/fetch-upstream-manifests.sh (ShadowsOverWestgate/sow-module#57), and
extended it to resolve the topdata channel as well. The script name is a
hardcoded path convention shared by both repos, not config, so the two sides
only work when they carry the same name.

Per #63 Decision 5 ("Coordinated rename flip") there is no transitional
symlink and no Go-side fallback: both sides flip and the short broken window
is accepted, because the failure is loud and unmistakable (required project
script is missing). A fallback would keep both names alive forever.

Closes #83

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

internal/app/app.go

@@ -385,7 +385,7 @@ func refreshBuildModuleManifest(ctx context, p *project.Project, progress func(s
 	}
 
 	progress("Refreshing hak list from the latest published sow-assets manifest...")
-	if err := runProjectScript(ctx, p, []string{"scripts", "fetch-hak-manifest"}, manifestPath); err != nil {
+	if err := runProjectScript(ctx, p, []string{"scripts", "fetch-upstream-manifests"}, manifestPath); err != nil {
 		return "", "", err
 	}
 	if _, err := pipeline.ApplyHAKManifest(p, manifestPath); err != nil {