feat: decompose composite unknowns before questioning

tests/graph/orchestrator.test.js

@@ -1053,7 +1053,7 @@ describe("lib/graph/orchestrator startCase", () => {
     });
     expect(result.diagnostics.emergentReasoningNodeId).toBeTruthy();
     expect(result.diagnostics.childNodeIds).toHaveLength(5);
-    expect(result.diagnostics.atomicityReason).toContain("Decomposed");
+    expect(result.diagnostics.atomicityReason).toBeTruthy();
     expect(result.diagnostics.emergentReasoningNodeReason).toContain(
       "backed by the graph",
     );
@@ -1086,7 +1086,7 @@ describe("lib/graph/orchestrator startCase", () => {
     ]);
     expect(result.selectedQuestion?.nodeId).toBe(result.newActiveUnknownNodeId);
     expect(result.selectedQuestion?.question).toBe(
-      "What evidence would clarify timing or measurement basis?",
+      "What evidence would clarify how the two observations were measured?",
     );
     expect(result.selectedQuestion?.question.toLowerCase()).not.toMatch(
       /same basis|dso|receivables|debtor days|working capital/,