feat: add image placeholders to blog post cards in /explore

- Show newspaper icon placeholder when blog posts don't have images
- Always render image container with consistent height
- Match the same placeholder style as large bookmark preview
- Improves visual consistency across the app

src/components/BlogPostCard.tsx

@@ -1,7 +1,7 @@
 import React from 'react'
 import { Link } from 'react-router-dom'
 import { FontAwesomeIcon } from '@fortawesome/react-fontawesome'
-import { faCalendar, faUser } from '@fortawesome/free-solid-svg-icons'
+import { faCalendar, faUser, faNewspaper } from '@fortawesome/free-solid-svg-icons'
 import { formatDistance } from 'date-fns'
 import { BlogPostPreview } from '../services/exploreService'
 import { useEventModel } from 'applesauce-react/hooks'
@@ -28,15 +28,19 @@ const BlogPostCard: React.FC<BlogPostCardProps> = ({ post, href }) => {
       className="blog-post-card"
       style={{ textDecoration: 'none', color: 'inherit' }}
     >
-      {post.image && (
-        <div className="blog-post-card-image">
+      <div className="blog-post-card-image">
+        {post.image ? (
           <img 
             src={post.image} 
             alt={post.title}
             loading="lazy"
           />
-        </div>
-      )}
+        ) : (
+          <div className="blog-post-image-placeholder">
+            <FontAwesomeIcon icon={faNewspaper} />
+          </div>
+        )}
+      </div>
       <div className="blog-post-card-content">
         <h3 className="blog-post-card-title">{post.title}</h3>
         {post.summary && (

src/styles/components/cards.css

@@ -77,9 +77,10 @@
 .explore-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(320px, 1fr)); gap: 2rem; margin-top: 2rem; }
 .blog-post-card { background: #1a1a1a; border: 1px solid #333; border-radius: 12px; overflow: hidden; transition: all 0.3s ease; cursor: pointer; display: flex; flex-direction: column; height: 100%; }
 .blog-post-card:hover { border-color: #646cff; transform: translateY(-4px); box-shadow: 0 8px 24px rgba(100, 108, 255, 0.15); }
-.blog-post-card-image { width: 100%; height: 200px; overflow: hidden; background: #0f0f0f; }
+.blog-post-card-image { width: 100%; height: 200px; overflow: hidden; background: #0f0f0f; display: flex; align-items: center; justify-content: center; }
 .blog-post-card-image img { width: 100%; height: 100%; object-fit: cover; transition: transform 0.3s ease; }
 .blog-post-card:hover .blog-post-card-image img { transform: scale(1.05); }
+.blog-post-image-placeholder { font-size: 3rem; color: #444; display: flex; align-items: center; justify-content: center; }
 .blog-post-card-content { padding: 1.5rem; display: flex; flex-direction: column; gap: 1rem; flex: 1; }
 .blog-post-card-title { font-size: 1.25rem; font-weight: 600; margin: 0; color: rgba(255, 255, 255, 0.95); line-height: 1.4; overflow: hidden; text-overflow: ellipsis; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; }
 .blog-post-card-summary { font-size: 0.875rem; color: rgba(255, 255, 255, 0.6); margin: 0; line-height: 1.6; overflow: hidden; text-overflow: ellipsis; display: -webkit-box; -webkit-line-clamp: 3; -webkit-box-orient: vertical; flex: 1; }