Fix financial taxonomy snapshot normalization

lib/server/financial-taxonomy.test.ts

@@ -1811,6 +1811,56 @@ describe('financial taxonomy internals', () => {
     });
   });
 
+  it('aggregates persisted detail rows when legacy snapshots are missing dimension arrays', () => {
+    const snapshot = {
+      ...createSnapshot({
+        filingId: 21,
+        filingType: '10-K',
+        filingDate: '2026-02-22',
+        statement: 'income',
+        periods: [
+          { id: '2025-fy', periodStart: '2025-01-01', periodEnd: '2025-12-31', periodLabel: '2025 FY' }
+        ]
+      }),
+      detail_rows: {
+        income: {
+          revenue: [{
+            key: 'revenue_detail',
+            parentSurfaceKey: 'revenue',
+            label: 'Revenue Detail',
+            conceptKey: 'us-gaap:RevenueDetail',
+            qname: 'us-gaap:RevenueDetail',
+            namespaceUri: 'http://fasb.org/us-gaap/2024',
+            localName: 'RevenueDetail',
+            unit: 'iso4217:USD',
+            values: { '2025-fy': 123_000_000 },
+            sourceFactIds: undefined,
+            isExtension: false,
+            dimensionsSummary: undefined,
+            residualFlag: false
+          } as unknown as FilingTaxonomySnapshotRecord['detail_rows']['income'][string][number]]
+        },
+        balance: {},
+        cash_flow: {},
+        equity: {},
+        comprehensive_income: {}
+      }
+    } satisfies FilingTaxonomySnapshotRecord;
+
+    const rows = __financialTaxonomyInternals.aggregateDetailRows({
+      snapshots: [snapshot],
+      statement: 'income',
+      selectedPeriodIds: new Set(['2025-fy'])
+    });
+
+    expect(rows.revenue).toHaveLength(1);
+    expect(rows.revenue?.[0]).toMatchObject({
+      key: 'revenue_detail',
+      sourceFactIds: [],
+      dimensionsSummary: []
+    });
+  });
+
   it('builds normalization metadata from snapshot fiscal pack and counts', () => {
     const snapshot = {
       ...createSnapshot({