Add payroll export functionality

[dhruvi-0406]

Summary

• Added payroll CSV export functionality
• Added /api/v1/payroll/export backend endpoint
• Added Swagger documentation for payroll export API
• Added payroll export integration in the Timesheets screen
• Added support for exporting payroll summaries by:
  • daily
  • weekly
  • monthly
• Added mobile sharing support using Expo Sharing
• Added loading and error handling for export flow

Testing

• Verified payroll summary API integration
• Verified payroll export endpoint response
• Verified CSV file generation flow
• Verified Android share sheet opens successfully after export
• Verified Swagger documentation renders correctly

Screenshots

Payroll API Endpoint

Payroll Export Swagger Documentation

Timesheets Export Button

Payroll Export Share Options

Export Success Message

[TeddyScript101]

Please review the existing implementation or refer to backend PR #319 for context.

You should not modify or update backend code as part of this work. There is a reason we are working as three separate teams with clearly defined responsibilities and ownership.

If you need support with the existing APIs, please reach out to the Backend team. When raising an issue, provide clear evidence such as:

Screenshots of the API requests/calls
Request payload
API response
Any relevant error details

This will help the team investigate and assist more efficiently.

[TeddyScript101]

Just a friendly reminder that you should be working on the payroll screen, not the timesheet screen.

On the other hand, this is not your first time making changes to others' code, like pushing notifications and notificationHelpers

Before you start coding those new blocks of code, make sure you’ve taken a look at the existing implementation for the guard app and backend. This will help you avoid any potential issues.

You’ve got one more chance to resubmit, so please take your time and double-check your work before sending it in. Rushing an update without proper verification can lead to mistakes.

Thanks a bunch for your cooperation!

[TeddyScript101]

I noticed you are still committing changes, but your updates continue to include unintended modifications, such as backend code changes, removal of features from the existing branch, and unwanted updates to existing logic.

This trimester already ended on 24 May, and no further updates are expected in order to keep the codebase stable for the next trimester.

Please take this as a learning opportunity to better understand how to submit proper pull requests and how file changes are reflected within a PR.