Add E2E Playwright tests for GLS-A/3F pay rule set scenarios

Three test scenarios covering pay rule set creation through UI,
working hours registration, Excel export, and pay code verification:
- Scenario 1: Standard Agriculture (WEEKDAY/SATURDAY/SUNDAY tiers)
- Scenario 2: Animal Care Weekend (DyrePasning with holiday type rule)
- Scenario 3: Apprentice Transition (Laerling U18 + Standard Voksen)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: renemadsen