Fix financial taxonomy snapshot normalization

lib/financials/statement-view-model.test.ts

@@ -160,6 +160,28 @@ describe('statement view model', () => {
     expect(child?.kind === 'surface' && child.expanded).toBe(true);
   });
 
+  it('does not throw when legacy surface rows are missing source arrays', () => {
+    const malformedRow = {
+      ...createSurfaceRow({ key: 'revenue', label: 'Revenue', category: 'revenue', values: { p1: 100 } }),
+      sourceConcepts: undefined,
+      sourceRowKeys: undefined
+    } as unknown as SurfaceFinancialRow;
+
+    const model = buildStatementTree({
+      surfaceKind: 'income_statement',
+      rows: [malformedRow],
+      statementDetails: null,
+      categories: [],
+      searchQuery: 'revenue',
+      expandedRowKeys: new Set()
+    });
+
+    expect(model.sections[0]?.nodes[0]).toMatchObject({
+      kind: 'surface',
+      row: { key: 'revenue' }
+    });
+  });
+
   it('keeps not meaningful rows visible and resolves selections for surface and detail nodes', () => {
     const rows = [
       createSurfaceRow({