[Feat]: Add multilingual Kokoro TTS support (specifically Russian language)

Is your feature request related to a problem?

Currently, the built-in Kokoro TTS engine in PocketPal AI on Android only supports English voices (e.g., Aya, Caccaro). When interacting with multilingual models in Russian, the local TTS feature stays silent or fails due to the lack of Russian phonetic tokenization in the default English weights.

Describe the solution you'd like

It would be fantastic to support multilingual capabilities for the Kokoro TTS implementation. Integrating Russian language support would drastically improve the experience for non-English users seeking a 100% offline neural voice experience.

Alternatively, adding an interface feature to manually load custom TTS files (.onnx / .bin voices and configs)—similar to how we load local GGUF models—would solve this permanently for all languages.

Reference Resources

For implementation, the following community pipelines, open-source weights, and multilingual architectures for Kokoro might be highly relevant:

• Base Architecture & Multilingual Weights: hexgrad/kokoro (supports v1.0+ multilingual pipelines).
• Russian Training Pipeline: igorshmukler/kokoro-ruslan (optimized Russian TTS training workflow using the Ruslan corpus).
• Multilingual Deployment Ref: 6Morpheus6/Kokoro-TTS-Multilingual (example of multi-language orchestration for Kokoro-82M).

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