fix(server): make startOfToday IST-aware

The client picks 'today' in IST local time but the server's
startOfToday() returned UTC midnight. For an IST user adding an
expense between 00:00 and 05:30 IST, the expense got stored on UTC
day X, and any later /expenses/today query (which used UTC again)
hit UTC day X+1 — empty. Meanwhile /expenses/by-date?date=<IST-today>
worked because the client sends the IST calendar date.

Shift now() by +5:30 before reading UTC components so 'today' on the
server matches what the IST client sees.

Author: lokeshwardewangan

server/src/shared/lib/date.ts

@@ -1,7 +1,11 @@
-// UTC midnight to avoid TZ drift on day boundaries.
+// UTC midnight of "today in IST" — the project ships only to IST users, and
+// the client picks dates in IST. Without this shift, expenses added between
+// 00:00 and 05:30 IST land on the previous UTC day, so /expenses/today
+// silently misses them while /expenses/by-date?date=<IST-today> finds them.
+const IST_OFFSET_MS = 5.5 * 60 * 60 * 1000;
 export const startOfToday = (): Date => {
-  const now = new Date();
-  return new Date(Date.UTC(now.getUTCFullYear(), now.getUTCMonth(), now.getUTCDate()));
+  const istNow = new Date(Date.now() + IST_OFFSET_MS);
+  return new Date(Date.UTC(istNow.getUTCFullYear(), istNow.getUTCMonth(), istNow.getUTCDate()));
 };
 
 export const startOfTomorrow = (): Date => {