Improve audio module test coverage to 80%+

[Orinks]

Summary

The audio module (player.py and tts_engine.py) has test coverage below 80%:

• player.py: 66% coverage
• tts_engine.py: 63% coverage

Uncovered Areas

player.py (lines 24-25, 28-29, 54-62, 85, 105, 121-123, 137-142, 152-154, 161-162, 176-177, 181-186)

1. sound_lib initialization/cleanup edge cases
2. Fallback playback path (playsound3)
3. Volume setting during active playback
4. Stream cleanup on stop/close

tts_engine.py (lines 22-24, 60-62, 79-81, 94-98, 179-185, 205-210, 222-238, 242-244)

1. Platform-specific TTS engine initialization
2. Speech synthesis error handling
3. Voice enumeration and selection
4. Async speech interruption

Labels

enhancement, tests

[Orinks]

Coverage target achieved. player.py: 94%, tts_engine.py: 97% (both well above 80% target). Completed via PR #10.