feat(ui): create idiomatic UI matching previous katbin iteration

Signed-off-by: SphericalKat <amolele@gmail.com>

lib/ketbin_web/templates/page/form.html.eex

@@ -0,0 +1,14 @@
+<%= form_for @changeset, @action, [class: "flex flex-col w-full h-full relative"], fn f -> %>
+    <%= if @changeset.action do %>
+        <div class="w-full text-center bg-amber">
+            <p>Oops, something went wrong!</p>
+        </div>
+    <% end %>
+
+    <div>
+        <%= textarea f, :content, [class: "w-full h-full px-6 py-4 outline-none bg-light-grey font-bold resize-none", placeholder: "> Paste, save, share! (Pasting just a URL will shorten it!)"] %>
+        <div class="absolute top-0 right-0 p-4">
+            <%= submit "Save" %>
+        </div>
+    </div>
+<% end %>

lib/ketbin_web/templates/page/index.html.eex

@@ -1,3 +1 @@
-<div>
-	hello, world!	
-</div>
+<%= render "form.html", Map.put(assigns, :action, Routes.page_path(@conn, :create)) %>