feat: improve accessibility and mobile responsiveness across UI components

Enhanced dialog accessibility by adding descriptive text to all dialog components. Implemented responsive layouts for mobile devices including card-based user table, adaptive navigation bar, and improved dialog spacing. Fixed Aliyun TTS health check to use WebSocket-based connectivity testing.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

qwen3-tts-frontend/src/components/users/ChangePasswordDialog.tsx

@@ -73,7 +73,7 @@ export function ChangePasswordDialog({
 
   return (
     <Dialog open={open} onOpenChange={handleOpenChange}>
-      <DialogContent className="sm:max-w-[425px]">
+      <DialogContent className="sm:max-w-[425px] max-h-[90vh] overflow-y-auto">
         <DialogHeader>
           <DialogTitle>修改密码</DialogTitle>
           <DialogDescription>
@@ -140,16 +140,17 @@ export function ChangePasswordDialog({
               )}
             />
 
-            <DialogFooter>
+            <DialogFooter className="flex-col sm:flex-row gap-2">
               <Button
                 type="button"
                 variant="outline"
                 onClick={() => handleOpenChange(false)}
                 disabled={isLoading}
+                className="w-full sm:w-auto"
               >
                 取消
               </Button>
-              <Button type="submit" disabled={isLoading}>
+              <Button type="submit" disabled={isLoading} className="w-full sm:w-auto">
                 {isLoading ? '提交中...' : '确认修改'}
               </Button>
             </DialogFooter>