Add render artifact model, config, and Seriatim adapter contracts

internal/artifacts/catalog_test.go

@@ -23,6 +23,26 @@ func TestArtifactCatalogRegisterBuiltInsAndLookup(t *testing.T) {
 	}
 }
 
+func TestArtifactCatalogRegisterBuiltInsIncludesMarkdownSources(t *testing.T) {
+	catalog := NewArtifactCatalog()
+	if err := catalog.RegisterBuiltIns(); err != nil {
+		t.Fatalf("RegisterBuiltIns() error = %v", err)
+	}
+
+	for _, sourceID := range []string{
+		ArtifactTranscriptFinalMarkdown,
+		ArtifactTranscriptFinalTrimmedMarkdown,
+	} {
+		entry, ok := catalog.Lookup(sourceID)
+		if !ok {
+			t.Fatalf("Lookup(%q) ok=false, want true", sourceID)
+		}
+		if !entry.Planned {
+			t.Fatalf("%s planned=false, want true", sourceID)
+		}
+	}
+}
+
 func TestArtifactCatalogRegisterConfiguredArtifactsDefaultsToEnabled(t *testing.T) {
 	catalog := NewArtifactCatalog()
 	if err := catalog.RegisterConfiguredArtifacts(map[string]ConfiguredArtifactDefinition{