Add All Shifts tab with apply flow for guards

[Krisha190235]

Summary

• added All tab to Shifts screen
• fetches all shifts from GET /api/v1/shifts
• added Apply button for available shifts
• kept Applied and Completed tabs unchanged
• reused existing shift card UI for consistency

API used

• GET /api/v1/shifts
• GET /api/v1/shifts/myshifts
• PUT /api/v1/shifts/{id}/apply

Notes

• All tab shows available and relevant shifts for guard
• Applied tab continues to show pending/confirmed shifts
• Completed tab continues to show completed shifts