feat: add /explore route to discover blog posts from friends

- Create exploreService to fetch kind:30023 events from followed users
- Add BlogPostCard component for displaying blog post previews
- Add Explore page component with grid layout
- Add /explore route to App.tsx (not linked in navigation yet)
- Add responsive CSS styles for explore page and blog post cards
- Clicking blog post cards navigates to article view

src/components/BlogPostCard.tsx

@@ -0,0 +1,59 @@
+import React from 'react'
+import { FontAwesomeIcon } from '@fortawesome/react-fontawesome'
+import { faCalendar, faUser } from '@fortawesome/free-solid-svg-icons'
+import { formatDistance } from 'date-fns'
+import { BlogPostPreview } from '../services/exploreService'
+import { Hooks } from 'applesauce-react'
+
+interface BlogPostCardProps {
+  post: BlogPostPreview
+  onClick: () => void
+}
+
+const BlogPostCard: React.FC<BlogPostCardProps> = ({ post, onClick }) => {
+  const profile = Hooks.useProfile(post.author)
+  const displayName = profile?.name || profile?.display_name || 
+    `${post.author.slice(0, 8)}...${post.author.slice(-4)}`
+  
+  const publishedDate = post.published || post.event.created_at
+  const formattedDate = formatDistance(new Date(publishedDate * 1000), new Date(), { 
+    addSuffix: true 
+  })
+
+  return (
+    <div 
+      className="blog-post-card"
+      onClick={onClick}
+      style={{ cursor: 'pointer' }}
+    >
+      {post.image && (
+        <div className="blog-post-card-image">
+          <img 
+            src={post.image} 
+            alt={post.title}
+            loading="lazy"
+          />
+        </div>
+      )}
+      <div className="blog-post-card-content">
+        <h3 className="blog-post-card-title">{post.title}</h3>
+        {post.summary && (
+          <p className="blog-post-card-summary">{post.summary}</p>
+        )}
+        <div className="blog-post-card-meta">
+          <span className="blog-post-card-author">
+            <FontAwesomeIcon icon={faUser} />
+            {displayName}
+          </span>
+          <span className="blog-post-card-date">
+            <FontAwesomeIcon icon={faCalendar} />
+            {formattedDate}
+          </span>
+        </div>
+      </div>
+    </div>
+  )
+}
+
+export default BlogPostCard
+