fix: allow multi-year income analytics periods

src/tbank/income-period.spec.ts

@@ -36,6 +36,17 @@ describe('income period planning', () => {
     ).toHaveLength(7);
   });
 
+  it('accepts multi-year periods and creates monthly buckets for the entire range', () => {
+    jest.useFakeTimers();
+    jest.setSystemTime(new Date('2026-09-09T12:00:00Z'));
+
+    const plan = planIncomePeriod('2020-01-01', '2025-12-31');
+    expect(plan.selected).toEqual({ from: '2020-01-01', to: '2025-12-31' });
+    expect(plan.granularity).toBe('month');
+    expect(rangeBuckets(plan.selected, plan.granularity)).toHaveLength(72);
+    expect(plan.yearAgo).toEqual({ from: '2019-01-01', to: '2024-12-31' });
+  });
+
   it('does not send the unfinished Moscow day as a future instant', () => {
     jest.useFakeTimers();
     jest.setSystemTime(new Date('2026-08-27T21:44:18.510Z'));

src/tbank/income-period.ts

@@ -101,8 +101,7 @@ function assertRange(range: DateOnlyRange, today: string): void {
   } catch {
     throw invalidPeriod();
   }
-  if (range.from > range.to || range.to > today || rangeDays(range) > 366)
-    throw invalidPeriod();
+  if (range.from > range.to || range.to > today) throw invalidPeriod();
 }
 
 function dateParts(value: string): [number, number, number] {