Fix timezone handling causing newly created events to disappear (#108)

[sakshibhatia17]

Summary

This PR fixes Issue #108.

Root Cause

The frontend extracted dates using toISOString().split('T')[0], which converts local time to UTC before extracting the date. For users in timezones ahead of UTC (e.g. IST), newly created events could be assigned to the previous calendar day, causing them to be filtered out from "My Events".

Additionally, the mock database could throw an error when iterating over events without attendees.

Changes

• Replaced toISOString().split('T')[0] with dayjs().format('YYYY-MM-DD') to preserve the user's local calendar date.
• Added a null check before iterating over event.attendees in the mock database.
• Removed all temporary debugging code.

Verification

• Created a new event and verified it appears immediately in My Events.
• Verified both frontend and backend build successfully.
• Confirmed the issue is resolved.

Fixes #108