Add TTS service input sanitization

[hman38705]

Issue 089: Add TTS service input sanitization

Area: TTS
Priority: High
Files: services/tts/src/TTSService.ts

Problem

TTS input text is passed to provider without sanitization. Malicious input could exploit provider APIs or inject SSML.

Acceptance Criteria

• Input text is sanitized before provider call\n- SSML injection is prevented\n- Maximum input length is enforced\n- Sanitization is tested

[itsjaneossai]

@itsjaneossai has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

I would like to work on this issue to help contribute.

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[El-Chapo-Npm]

@El-Chapo-Npm has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

Hello team, i would like to work on this issue

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[drips-wave]

Congratulations, @El-Chapo-Npm! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on April 29, 2026.

🧑‍💻 @El-Chapo-Npm: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

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[drips-wave]

This issue has been completed by @El-Chapo-Npm as part of the Stellar Wave Program's 4th Wave 🥳

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