fix(progress-tracker): allow revoke_delegation during emergency pause (#492)

[lmduy2612]

Summary of Changes

Closes #492.

This PR enables learners to revoke progress delegations during an emergency pause in contracts/progress-tracker:

• Safety rationale: The emergency pause is designed to freeze state-mutating actions that add risk (e.g. submitting progress, completing modules, or creating delegations). Revoking a delegation is a safety-critical action that eliminates risk by immediately cutting off compromised or malicious delegates.
• Implementation:
  • Removed Self::require_not_paused(&env); from revoke_delegation in contracts/progress-tracker/src/lib.rs.
  • Preserved Self::require_not_paused(&env); on delegate_progress, ensuring new delegations remain strictly blocked during pause.
• Tests:
  • Added unit test test_revoke_delegation_succeeds_while_paused in tests/unit/progress_tests.rs.
  • Added integration test assertions to test_progress_tracker_emergency_pause in tests/integration/emergency_pause_flow.rs covering pause -> delegate attempt failure -> revoke delegation success -> state verification.

Verification

• cargo test --test progress_tests: All 107 tests passing.
• cargo test --test emergency_pause_flow: All 4 tests passing.
• Clippy: 0 warnings on modified files.