test(cli): cover artifact_uri render lines (#248 Phase 3)

The Artifact: display lines added to formatTaskDetail / formatStatusSnapshot
introduced uncovered truthy branches that dropped CLI branch coverage below the
84% gate (full `mise run build` caught it; the per-package run had passed on the
prior content). Adds non-null + null cases for both renderers, mirroring the
existing trace_s3_uri tests. cli 300 passed; full build green.

Author: bgagent

cli/test/format-status-snapshot.test.ts

@@ -315,6 +315,18 @@ describe('formatStatusSnapshot', () => {
     expect(rendered).not.toContain('Trace S3:');
   });
 
+  test('renders Artifact line when artifact_uri is non-null (#248 Phase 3)', () => {
+    const task = buildTask({ artifact_uri: 's3://artifacts-bkt/artifacts/abc123/result.md' });
+    const rendered = formatStatusSnapshot(task, [], NOW);
+    expect(rendered).toContain('Artifact:      s3://artifacts-bkt/artifacts/abc123/result.md');
+  });
+
+  test('omits Artifact line when artifact_uri is null', () => {
+    const task = buildTask();
+    const rendered = formatStatusSnapshot(task, [], NOW);
+    expect(rendered).not.toContain('Artifact:');
+  });
+
   // ---- Workflow + Reason (PR #52 CLI UX carry-forward) ----
 
   test('renders Workflow line for pr_iteration tasks with PR number', () => {

cli/test/format.test.ts

@@ -142,6 +142,20 @@ describe('format', () => {
       expect(output).not.toContain('Trace S3:');
     });
 
+    test('renders Artifact line when artifact_uri is non-null (#248 Phase 3)', () => {
+      const withArtifact: TaskDetail = {
+        ...task,
+        artifact_uri: 's3://artifacts-bkt/artifacts/abc123/result.md',
+      };
+      const output = formatTaskDetail(withArtifact);
+      expect(output).toContain('Artifact:    s3://artifacts-bkt/artifacts/abc123/result.md');
+    });
+
+    test('omits Artifact line when artifact_uri is null', () => {
+      const output = formatTaskDetail(task);
+      expect(output).not.toContain('Artifact:');
+    });
+
     test('shows classified error with raw detail when error_classification is present', () => {
       const failedTask: TaskDetail = {
         ...task,