refactor: migrate img tags to next/image and fix hook usage

src/app/chat/components/image-bubble.tsx

@@ -9,6 +9,7 @@
  *   - 点击 → 打开全屏查看器
  *   - 错误占位符（broken image icon）
  */
+import Image from "next/image";
 import { useState } from "react";
 
 import { FullscreenImageViewer } from "./fullscreen-image-viewer";
@@ -42,11 +43,12 @@ export function ImageBubble({ imageUrl }: ImageBubbleProps) {
         {error ? (
           <div className={styles.errorFallback}>🖼</div>
         ) : (
-          // eslint-disable-next-line @next/next/no-img-element
-          <img
+          <Image
             className={styles.image}
             src={src}
             alt=""
+            width={240}
+            height={240}
             onError={() => setError(true)}
           />
         )}