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.ts

@@ -292,7 +292,7 @@ export class TbankClient {
       {
         instrumentId,
         from: { seconds: String(utcSeconds(from)) },
-        to: { seconds: String(utcSeconds(to)) },
+        to: { seconds: String(utcSeconds(to, true)) },
       },
     ).then((response) => response.dividends ?? []);
   }
@@ -344,7 +344,7 @@ export class TbankClient {
       {
         instrumentId: uid,
         from: { seconds: String(utcSeconds(from)) },
-        to: { seconds: String(utcSeconds(to)) },
+        to: { seconds: String(utcSeconds(to, true)) },
       },
     ).then((response) => response.events ?? []);
   }
@@ -552,6 +552,9 @@ export class TbankClient {
   }
 }
 
-function utcSeconds(date: string): number {
-  return Math.floor(Date.parse(`${date}T00:00:00Z`) / MILLISECONDS_PER_SECOND);
+// Calendar owners supply inclusive UTC days; RPC timestamps use [from, next(to)).
+function utcSeconds(date: string, nextDay = false): number {
+  const instant = new Date(`${date}T00:00:00Z`);
+  if (nextDay) instant.setUTCDate(instant.getUTCDate() + 1);
+  return Math.floor(instant.valueOf() / MILLISECONDS_PER_SECOND);
 }