Refactor app in to its own slice

slices/main/templates/posts/archive.html.slim

@@ -0,0 +1,16 @@
+div class="mb-4 prose dark:prose-invert max-w-prose mx-auto text-gray-800 dark:text-gray-200"
+  h1 Archive: #{year}
+
+div class="mb-12 max-w-prose mx-auto text-gray-800 dark:text-gray-200"
+  nav class="space-x-1 text-sm md:text-sm uppercase md:block"
+    span Archive:
+    - post_years.each do |y|
+      a href="/posts/archive/#{y}" class="text-sm hover:text-gray-400 #{year.to_s == y.to_s ? 'underline decoration-wavy' : ''}"= y
+      - if y != post_years.last
+        span ·
+div class="h-feed mb-12 max-w-prose mx-auto"
+  - posts.each do |post|
+    == render "shared/post", post: post
+
+div class="max-w-screen-md mx-auto border-t border-solid border-gray-200 dark:border-gray-600"
+