Unify tutorial: update tutorial flow unit tests #764

Summary

Update tests/main-street/tutorial-flow.test.ts to cover the unified tutorial controller with the merged step set (13 steps). All existing tests must continue to pass, and new tests must verify the new behavior.

Acceptance Criteria

• All existing unit tests for TutorialFlow.ts pass
• New tests cover:
  • Unified controller state transitions (start, advance, complete, exit)
  • Step resolution for both gate types (confirm vs action)
  • isRequiredAction() and shouldAllowAction() with the merged step set
  • getCurrentStep() returns correct step by ID
  • Tutorial completion (past step 13) returns null for getCurrentStep()
• Pure controller tests remain headless (no Phaser dependency)

Dependencies

• None (this is the first implementation task, but tests must exist before the implementation they validate is written)