UX: Improvements to posts route (#30968)

This update makes some small improvements to the posts route front-end.
Specifically, it adds a title to the page, and it improves the
positioning of expand/collapse caret.

spec/system/page_objects/pages/posts_page.rb

@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+module PageObjects
+  module Pages
+    class Posts < PageObjects::Pages::Base
+      POSTS_PAGE_SELECTOR = ".posts-page"
+
+      def visit
+        page.visit("/posts")
+        self
+      end
+
+      def has_page_title?
+        page.find("#{POSTS_PAGE_SELECTOR} .posts-page__title")
+      end
+
+      def has_posts?(count)
+        page.has_css?("#{POSTS_PAGE_SELECTOR} .post-list .post-list-item", count: count)
+      end
+    end
+  end
+end

spec/system/posts_page_spec.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+describe "Posts page", type: :system do
+  fab!(:post)
+  fab!(:post_2) { Fabricate(:post) }
+  fab!(:post_3) { Fabricate(:post) }
+  fab!(:user)
+  let(:posts_page) { PageObjects::Pages::Posts.new }
+
+  before { sign_in(user) }
+
+  it "renders the posts page with posts" do
+    posts_page.visit
+    expect(posts_page).to have_page_title
+    expect(posts_page).to have_posts(3)
+  end
+end