show_monologue() now returns early when text.is_empty(), preventing: - ghost visible slots with blank labels - stagger timer advancing on empty calls - empty strings queuing when slots are full Tests: add test_show_monologue_with_empty_text_does_not_set_displaying and two companion cases (stagger timer unchanged, no enqueue when full) anticipating Hoshe's QA additions to the test suite. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>