Introduce a few system tests

Primarily I'm trying to exercise active storage and action cable /
turbo streams, both of which have been brittle when making changes to
tenanting.

test/system/smoke_test.rb

@@ -0,0 +1,67 @@
+require "application_system_test_case"
+
+class SmokeTest < ApplicationSystemTestCase
+  test "create a card" do
+    sign_in_as(users(:david))
+
+    visit cards_url(collection_ids: [ collections(:writebook).id ])
+    click_on "Add a card"
+    fill_in "card_title", with: "Hello, world!"
+    fill_in_lexxy with: "I am editing this thing"
+    click_on "Create card"
+
+    assert_selector "h1", text: "Hello, world!"
+  end
+
+  test "active storage attachments" do
+    sign_in_as(users(:david))
+
+    visit card_url(cards(:layout))
+    fill_in_lexxy with: "Here is a comment"
+    attach_file file_fixture("moon.jpg") do
+      click_on "Upload file"
+    end
+
+    assert_image_figure_attachment content_type: "image/jpeg", caption: "moon.jpg"
+
+    click_on "Post this comment"
+
+    assert_image_figure_attachment content_type: "image/jpeg", caption: "moon.jpg"
+  end
+
+  test "dismissing notifications" do
+    sign_in_as(users(:david))
+
+    notif = notifications(:logo_card_david_mention_by_jz)
+
+    assert_selector "div##{dom_id(notif)}"
+
+    within_window(open_new_window) { visit card_url(notif.card) }
+
+    assert_no_selector "div##{dom_id(notif)}"
+  end
+
+  private
+    def sign_in_as(user)
+      visit session_transfer_url(user.transfer_id)
+      assert_selector "h1", text: "Activity"
+    end
+
+    def fill_in_lexxy(selector = "lexxy-editor", with:)
+      editor_element = find(selector)
+      editor_element.set with
+      page.execute_script("arguments[0].value = '#{with}'", editor_element)
+    end
+
+    def assert_figure_attachment(content_type:, &block)
+      figure = find("figure.attachment[data-content-type='#{content_type}']")
+      within(figure, &block) if block_given?
+    end
+
+    def assert_image_figure_attachment(content_type: "image/png", caption:)
+      assert_figure_attachment(content_type: content_type) do
+        assert_selector("img[src*='/rails/active_storage']")
+        assert_selector "figcaption input[placeholder='#{caption}']"
+      end
+    end
+end