feat: add Chatterbox TTS engine for multilingual voice cloning

- New ChatterboxTTSBackend wrapping ChatterboxMultilingualTTS (ResembleAI/chatterbox)
- Supports 23 languages including Hebrew, forces CPU on macOS (MPS issue)
- Monkey-patches torch.load for CPU loading, forces eager attention for compatibility
- trim_tts_output utility cuts trailing silence/hallucination from Chatterbox output
- Full engine integration: /generate, /generate/stream, model status/download/delete
- Hebrew (he) added to supported languages in frontend and backend validation
- Single flat model dropdown extended with Chatterbox option in both generation UIs
- ModelManagement UI groups LuxTTS and Chatterbox under 'Other Voice Models' section

app/src/lib/constants/languages.ts

@@ -1,6 +1,6 @@
 /**
- * Supported languages for Qwen3-TTS
- * Based on: https://github.com/QwenLM/Qwen3-TTS
+ * Supported languages for voice generation.
+ * Most languages use Qwen3-TTS; Hebrew uses Chatterbox TTS.
  */
 
 export const SUPPORTED_LANGUAGES = {
@@ -14,6 +14,7 @@ export const SUPPORTED_LANGUAGES = {
   pt: 'Portuguese',
   es: 'Spanish',
   it: 'Italian',
+  he: 'Hebrew',
 } as const;
 
 export type LanguageCode = keyof typeof SUPPORTED_LANGUAGES;