Disable Unit destuction for base units with subunits

Closes #40

app/controllers/default/units_controller.rb

@@ -12,7 +12,7 @@ class Default::UnitsController < ApplicationController
   end
 
   def index
-    @units = current_user.units.defaults_diff.includes(:base).ordered
+    @units = current_user.units.defaults_diff.includes(:base).includes(:subunits).ordered
   end
 
   def import

app/controllers/units_controller.rb

@@ -9,7 +9,7 @@ class UnitsController < ApplicationController
   end
 
   def index
-    @units = current_user.units.includes(:subunits).ordered
+    @units = current_user.units.includes(:base).includes(:subunits).ordered
   end
 
   def new

app/views/default/units/_unit.html.erb

@@ -12,7 +12,7 @@
       <% if current_user.at_least(:admin) %>
         <% if unit.default? %>
           <%= image_button_to t('.delete'), 'delete-outline', default_unit_path(unit),
-            method: :delete %>
+            method: :delete, **disabled_attributes(!unit.movable?) %>
         <% else %>
           <%= image_button_to t('.export'), 'upload-outline', export_default_unit_path(unit),
             disabled_attributes(!unit.portable?) %>

app/views/units/_unit.html.erb

@@ -17,8 +17,8 @@
           id: dom_id(unit, :new, :link), onclick: 'this.blur();', data: {turbo_stream: true} %>
       <% end %>
 
-      <%= image_button_to t('.delete_unit'), 'delete-outline', unit_path(unit),
-        method: :delete %>
+      <%= image_button_to t('.destroy'), 'delete-outline', unit_path(unit),
+        method: :delete, **disabled_attributes(!unit.movable?) %>
     </td>
     <% if unit.movable? %>
       <td class="handle" draggable="true">&#x283F</td>