fix: 限制 Markdown 内容中图片的显示大小

用容器包裹图片并设置最大宽度为 max-w-md (448px)，避免超大图片影响页面阅读体验。

src/components/project/MarkdownContent.tsx

@@ -214,15 +214,19 @@ const components: Components = {
     </a>
   ),
 
-  // Images
+  // Images - wrapped in container for size control
   img: ({ src, alt, ...props }) => (
-    <img
-      src={src}
-      alt={alt}
-      className="rounded-lg border border-gray-300 dark:border-gray-600 my-4 max-w-full h-auto"
-      loading="lazy"
-      {...props}
-    />
+    <div className="my-4 flex justify-center">
+      <div className="max-w-md w-full">
+        <img
+          src={src}
+          alt={alt}
+          className="rounded-lg border border-gray-300 dark:border-gray-600 w-full h-auto object-contain"
+          loading="lazy"
+          {...props}
+        />
+      </div>
+    </div>
   ),
 
   // Horizontal rule