Update the analyze stage to utilize the new artifact package

internal/config/scriptorium_test.go

@@ -116,6 +116,37 @@ func TestScriptoriumLoadAndValidate(t *testing.T) {
         output_kind: session_recap
 `,
 		},
+		{
+			name: "canonical artifact source is accepted",
+			scriptoriumYAML: `scriptorium:
+  binary: scriptorium
+  artifacts:
+    session_recap:
+      enabled: true
+      prompt_id: dnd.session_recap
+      output_path: artifacts/session_recap.md
+      inputs:
+        transcript:
+          source: narratio.transcript.trimmed
+          required: true
+`,
+		},
+		{
+			name: "unknown artifact source fails validation",
+			scriptoriumYAML: `scriptorium:
+  binary: scriptorium
+  artifacts:
+    session_recap:
+      enabled: true
+      prompt_id: dnd.session_recap
+      output_path: artifacts/session_recap.md
+      inputs:
+        transcript:
+          source: narratio.unknown
+          required: true
+`,
+			wantValidateErr: `pipeline.scriptorium.artifacts.session_recap.inputs.transcript.source "narratio.unknown" is unsupported`,
+		},
 		{
 			name: "artifact render_debug override is accepted",
 			scriptoriumYAML: `scriptorium: