Refactor UserPortal Events screen to use DateRangePicker for filtering

[coderabbitai]

Overview

Integrate DateRangePicker into UserPortal/Events/Events.tsx for event date filtering. Adds optional preset ranges for quick selections.

Related Issues

• Depends on: #
• Foundation: Talawa Admin - Refactoring (2025 - 2026) - Part 1 #5022

Files to Update

• src/screens/UserPortal/Events/Events.tsx - Replace startAt/endAt with DateRangePicker
• src/screens/UserPortal/Events/Events.spec.tsx - Update tests

Dependencies

• Blocked by: # (DateRangePicker component creation)

Acceptance Criteria

• DateRangePicker integrated for date filtering
• startAt/endAt state replaced with dateRange
• Optional preset ranges added (e.g., "This Week", "This Month")
• GraphQL query variables receive formatted dates
• Event filtering by date range works
• All tests updated and passing

Testing Checklist

• Date range filter updates event list
• Preset ranges work correctly
• GraphQL query receives correct date parameters
• Event calendar updates based on date range

Estimated Effort

8 hours

Implementation Notes

• Add presets for common ranges: "Today", "This Week", "This Month"
• Ensure calendar view updates when date range changes
• Keep existing dayjs formatting for query variables