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/components/Generation/FloatingGenerateBox.tsx

@@ -316,7 +316,7 @@ export function FloatingGenerateBox({
                   </span>
                 </div>
                 <AnimatePresence>
-                  {isExpanded && form.watch('engine') !== 'luxtts' && (
+                  {isExpanded && form.watch('engine') === 'qwen' && (
                     <motion.div
                       initial={{ opacity: 0, scale: 0.8 }}
                       animate={{ opacity: 1, scale: 1 }}
@@ -407,11 +407,15 @@ export function FloatingGenerateBox({
                       value={
                         form.watch('engine') === 'luxtts'
                           ? 'luxtts'
-                          : `qwen:${form.watch('modelSize') || '1.7B'}`
+                          : form.watch('engine') === 'chatterbox'
+                            ? 'chatterbox'
+                            : `qwen:${form.watch('modelSize') || '1.7B'}`
                       }
                       onValueChange={(value) => {
                         if (value === 'luxtts') {
                           form.setValue('engine', 'luxtts');
+                        } else if (value === 'chatterbox') {
+                          form.setValue('engine', 'chatterbox');
                         } else {
                           const [, modelSize] = value.split(':');
                           form.setValue('engine', 'qwen');
@@ -434,6 +438,9 @@ export function FloatingGenerateBox({
                         <SelectItem value="luxtts" className="text-xs text-muted-foreground">
                           LuxTTS
                         </SelectItem>
+                        <SelectItem value="chatterbox" className="text-xs text-muted-foreground">
+                          Chatterbox
+                        </SelectItem>
                       </SelectContent>
                     </Select>
                   </FormItem>