fix: resolve code quality and consistency issues in Kokoro TTS connector

[Wanbogang]

Issues Found

1. Duplicate IOProvider initialization - self.io_provider = IOProvider() called twice
2. Uninitialized variable - self._zenoh_tts_status_response_pub used before declaration
3. Inconsistent variable naming - using ai_status_response instead of tts_status_response
4. Incorrect logging messages - still using "Elevenlabs TTS" instead of "Kokoro TTS"
5. Missing error handling - zenoh callback methods have no try-catch blocks
6. Missing null checks - publisher used without validation

Fixes Applied

• Remove duplicate IOProvider initialization, keep only one instance
• Add self._zenoh_tts_status_response_pub = None at the beginning of init
• Change all ai_status_response to tts_status_response
• Update all log messages to "Kokoro TTS"
• Add try-catch blocks in zenoh_audio_message() and _zenoh_tts_status_request()
• Add if self._zenoh_tts_status_response_pub: check before publishing

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ All tests successful. No failed tests found.

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