fix(investments): align roles and date contracts

Identify income dependencies by role and document screen-specific dates.
Convert inclusive calendar days into half-open source ranges while
preserving operation timestamps and existing stored coverage.

src/integrations/tbank/tbank.client.spec.ts

@@ -46,11 +46,26 @@ describe('TbankClient operations', () => {
         seconds: String(Math.floor(Date.parse('2026-08-19T00:00:00Z') / 1000)),
       },
       to: {
-        seconds: String(Math.floor(Date.parse('2026-09-18T00:00:00Z') / 1000)),
+        seconds: String(Math.floor(Date.parse('2026-09-19T00:00:00Z') / 1000)),
       },
     });
   });
 
+  it.each(['getDividends', 'getBondCoupons'] as const)(
+    '%s converts a leap-day calendar window to a full half-open UTC day',
+    async (method) => {
+      const client = Object.create(TbankClient.prototype) as TbankClient;
+      const call = jest.fn().mockResolvedValue({});
+      (client as unknown as { call: jest.Mock }).call = call;
+      await client[method]('token', 'uid', '2024-02-29', '2024-02-29');
+      expect(call).toHaveBeenCalledWith('token', undefined, method, {
+        instrumentId: 'uid',
+        from: { seconds: String(Date.parse('2024-02-29T00:00:00Z') / 1000) },
+        to: { seconds: String(Date.parse('2024-03-01T00:00:00Z') / 1000) },
+      });
+    },
+  );
+
   it('propagates the normalized upstream error', async () => {
     const client = Object.create(TbankClient.prototype) as TbankClient;
     const error = new ServiceUnavailableException({