Implement measurements create/destroy and display existing readouts

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/views/measurements/_readout.html.erb

@@ -0,0 +1,12 @@
+<%= tag.tr id: dom_id(readout) do %>
+  <td><%= readout.quantity %></td>
+  <td class="ralign"><%= readout.value %></td>
+  <td><%= readout.unit %></td>
+  <td><%= l(readout.created_at) %></td>
+  <% if current_user.at_least(:active) %>
+    <td class="flex">
+      <%= image_button_to t('.destroy'), 'delete-outline', measurement_path(readout),
+        method: :delete, data: {turbo_stream: true} %>
+    </td>
+  <% end %>
+<% end %>