feat: update user preferences and system settings management

qwen3-tts-frontend/src/components/tts/VoiceCloneForm.tsx

@@ -38,7 +38,6 @@ const formSchema = z.object({
   top_k: z.number().min(1).max(100).optional(),
   top_p: z.number().min(0).max(1).optional(),
   repetition_penalty: z.number().min(0).max(2).optional(),
-  backend: z.string().optional(),
 })
 
 type FormData = z.infer<typeof formSchema>
@@ -78,16 +77,9 @@ function VoiceCloneForm() {
       top_k: 20,
       top_p: 0.7,
       repetition_penalty: 1.05,
-      backend: preferences?.default_backend || 'local',
     } as Partial<FormData>,
   })
 
-  useEffect(() => {
-    if (preferences?.default_backend) {
-      setValue('backend', preferences.default_backend)
-    }
-  }, [preferences?.default_backend, setValue])
-
   useEffect(() => {
     const fetchData = async () => {
       try {
@@ -243,22 +235,6 @@ function VoiceCloneForm() {
 
       <div className={step === 2 ? 'block space-y-4' : 'hidden'}>
         {/* Step 2: Synthesis Options */}
-        <div className="space-y-0.5">
-          <Label>后端选择</Label>
-          <Select
-            value={watch('backend')}
-            onValueChange={(value: string) => setValue('backend', value)}
-          >
-            <SelectTrigger>
-              <SelectValue />
-            </SelectTrigger>
-            <SelectContent>
-              <SelectItem value="local">本地模型</SelectItem>
-              <SelectItem value="aliyun">阿里云 API</SelectItem>
-            </SelectContent>
-          </Select>
-        </div>
-
         <div className="space-y-0.5">
           <IconLabel icon={Globe2} tooltip="语言（可选）" />
           <Select