fix(chat): fix type error and indentation in reconnect/scroll-lock change

- useChat.ts reconnectStream: cast the reused assistant message id to string
  when calling updateMessage; the id is optional in the Message type, so the
  raw value broke the vue-tsc build (TS2345, undefined not assignable).
- useStickToBottom.ts handleScroll: restore the block's indentation (it had
  drifted to 1/3-space) and add a comment for the scroll-up release branch.

Verified: vue-tsc --noEmit passes; snowflake precision check clean.

mateclaw-ui/src/composables/chat/useChat.ts

@@ -2060,7 +2060,7 @@ export function useChat(options: UseChatOptions): UseChatReturn {
         && (m.status === 'generating' || m.status === 'awaiting_approval')
     )
     if (existingAsst) {
-      updateMessage(existingAsst.id, {
+      updateMessage(existingAsst.id as string, {
         ...existingAsst,
         content: '',
         contentParts: [],

mateclaw-ui/src/composables/chat/useStickToBottom.ts

@@ -127,9 +127,11 @@ export function useStickToBottom(
   }
 
   // 处理滚动事件
- const handleScroll = () => {
-   if (!scrollRef.value) return
-   if (isScrolling) {
+  const handleScroll = () => {
+    if (!scrollRef.value) return
+    if (isScrolling) {
+      // User scrolled up during a programmatic scroll — release the lock so the
+      // view stops snapping back to the bottom.
       const currentScrollTop = scrollRef.value.scrollTop
       if (currentScrollTop < lastScrollTop) {
         isScrolling = false
@@ -138,7 +140,7 @@ export function useStickToBottom(
       }
       lastScrollTop = scrollRef.value.scrollTop
       return
-   }
+    }
 
     const element = scrollRef.value
     const currentScrollTop = element.scrollTop