fix(blog): show full cover image with object-fit: contain

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: grantzhou

src/css/custom.css

@@ -324,13 +324,13 @@
 .blog-card-img {
   width: 100%;
   height: 100%;
-  object-fit: cover;
+  object-fit: contain;
   display: block;
   transition: transform 0.4s;
 }
 
 .blog-card:hover .blog-card-img {
-  transform: scale(1.04);
+  transform: scale(1.02);
 }
 
 .blog-card-img-placeholder {