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/index.css

@@ -2555,3 +2555,163 @@ body {
 .three-pane.sidebar-collapsed .relay-status-indicator {
   left: calc(var(--sidebar-collapsed-width) + 1.5rem);
 }
+
+/* Explore Page Styles */
+.explore-container {
+  padding: 2rem;
+  max-width: 1400px;
+  margin: 0 auto;
+  min-height: 100vh;
+}
+
+.explore-header {
+  text-align: center;
+  margin-bottom: 3rem;
+}
+
+.explore-header h1 {
+  font-size: 2.5rem;
+  margin: 0 0 1rem 0;
+  color: #646cff;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  gap: 1rem;
+}
+
+.explore-subtitle {
+  font-size: 1.125rem;
+  color: rgba(255, 255, 255, 0.7);
+  margin: 0;
+}
+
+.explore-loading,
+.explore-error {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  justify-content: center;
+  gap: 1rem;
+  min-height: 50vh;
+  color: rgba(255, 255, 255, 0.7);
+}
+
+.explore-error {
+  color: #ff6b6b;
+}
+
+.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 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-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;
+}
+
+.blog-post-card-meta {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 1rem;
+  padding-top: 0.75rem;
+  border-top: 1px solid #333;
+  font-size: 0.75rem;
+  color: rgba(255, 255, 255, 0.5);
+  flex-wrap: wrap;
+}
+
+.blog-post-card-author,
+.blog-post-card-date {
+  display: flex;
+  align-items: center;
+  gap: 0.5rem;
+}
+
+.blog-post-card-author svg,
+.blog-post-card-date svg {
+  opacity: 0.7;
+}
+
+@media (max-width: 768px) {
+  .explore-container {
+    padding: 1rem;
+  }
+
+  .explore-header h1 {
+    font-size: 2rem;
+  }
+
+  .explore-grid {
+    grid-template-columns: 1fr;
+    gap: 1.5rem;
+  }
+}