feat(chat): make ThinkingBlock title support i18n via label prop

Add optional label prop to ThinkingBlock with default value 'Thinking',
and pass the translated string from web layer using thinking.thinkingProcess key.

Author: qjp88995

packages/ui/src/chat/thinking-block.tsx

@@ -13,6 +13,7 @@ type ThinkingBlockProps = {
   children: React.ReactNode;
   defaultOpen?: boolean;
   className?: string;
+  label?: string;
 };
 
 function ThinkingBlock({
@@ -21,6 +22,7 @@ function ThinkingBlock({
   children,
   defaultOpen = false,
   className,
+  label = 'Thinking',
 }: ThinkingBlockProps) {
   const [open, setOpen] = React.useState(defaultOpen);
   const contentRef = React.useRef<HTMLDivElement>(null);
@@ -65,7 +67,7 @@ function ThinkingBlock({
             open && 'rotate-90'
           )}
         />
-        <span>Thinking</span>
+        <span>{label}</span>
         {duration != null && (
           <span className="text-foreground-ghost ml-0.5">
             &middot; {duration}s

packages/web/src/components/chat/message-item.tsx

@@ -189,6 +189,7 @@ function AssistantContent({ parts }: { readonly parts: UIMessage['parts'] }) {
               key={`reasoning-${i}`}
               isStreaming={rp.state !== 'done'}
               defaultOpen={rp.state !== 'done'}
+              label={t('thinking.thinkingProcess')}
             >
               <div className="whitespace-pre-wrap">{rp.text || '...'}</div>
             </ThinkingBlock>