FIX: add decorated html to edit sidebar categories (#37169)

Fixes a display issue in the edit sidebar category modal where
categories contain hashtags for either tags, categories etc.

This change adds decorated html to allow hashtag decoration on category
descriptions.

### Before

<img width="510" height="210" alt="Before change"
src="https://github.com/user-attachments/assets/58673ed6-fb6a-4bbb-986e-ec3f8759a619"
/>


### After

<img width="500" height="209" alt="After change"
src="https://github.com/user-attachments/assets/2e665829-b6bb-45da-9762-9eb0ba87ef45"
/>

frontend/discourse/app/components/sidebar/edit-navigation-menu/categories-modal.gjs

@@ -7,6 +7,7 @@ import didInsert from "@ember/render-modifiers/modifiers/did-insert";
 import { service } from "@ember/service";
 import { TrackedSet } from "@ember-compat/tracked-built-ins";
 import ConditionalLoadingSpinner from "discourse/components/conditional-loading-spinner";
+import DecoratedHtml from "discourse/components/decorated-html";
 import EditNavigationMenuModal from "discourse/components/sidebar/edit-navigation-menu/modal";
 import borderColor from "discourse/helpers/border-color";
 import categoryBadge from "discourse/helpers/category-badge";
@@ -299,10 +300,12 @@ export default class SidebarEditNavigationMenuCategoriesModal extends Component
                         <div
                           class="sidebar-categories-form__category-description"
                         >
-                          {{dirSpan
-                            category.description_excerpt
-                            htmlSafe="true"
-                          }}
+                          <DecoratedHtml
+                            @html={{dirSpan
+                              category.description_excerpt
+                              htmlSafe="true"
+                            }}
+                          />
                         </div>
                       {{/unless}}
                     </div>

spec/system/editing_sidebar_categories_navigation_spec.rb

@@ -184,6 +184,33 @@ RSpec.describe "Editing sidebar categories navigation", type: :system do
     )
   end
 
+  describe "hashtag decoration in category descriptions" do
+    fab!(:tag) { Fabricate(:tag, name: "test-tag") }
+    fab!(:icon_category) { Fabricate(:category, name: "icon category", icon: "wrench") }
+    fab!(:emoji_category) { Fabricate(:category, name: "emoji category", emoji: "rocket") }
+
+    fab!(:category_with_hashtags) do
+      Fabricate(:category, name: "category with hashtags", description: <<~HTML)
+          Discussion about
+          and <a class="hashtag-cooked" href="/tag/#{tag.name}" data-type="tag" data-slug="#{tag.name}" data-id="#{tag.id}"><span class="hashtag-icon-placeholder"></span><span>#{tag.name}</span></a>
+          and <a class="hashtag-cooked" href="/c/#{icon_category.slug}/#{icon_category.id}" data-type="category" data-slug="#{icon_category.slug}" data-id="#{icon_category.id}" data-style-type="icon" data-icon="wrench"><span class="hashtag-icon-placeholder"></span><span>#{icon_category.name}</span></a>
+          and <a class="hashtag-cooked" href="/c/#{emoji_category.slug}/#{emoji_category.id}" data-type="category" data-slug="#{emoji_category.slug}" data-id="#{emoji_category.id}" data-style-type="emoji" data-emoji="rocket"><span class="hashtag-icon-placeholder"></span><span>#{emoji_category.name}</span></a>
+        HTML
+    end
+
+    it "decorates hashtags for tags, icons and emojis in the description" do
+      visit "/latest"
+
+      expect(sidebar).to have_categories_section
+
+      modal = sidebar.click_edit_categories_button
+
+      expect(modal).to have_tag_in_description(category_with_hashtags)
+      expect(modal).to have_icon_in_description(category_with_hashtags)
+      expect(modal).to have_emoji_in_description(category_with_hashtags)
+    end
+  end
+
   describe "when max_category_nesting has been set to 3" do
     before_all { SiteSetting.max_category_nesting = 3 }
 

spec/system/page_objects/modals/sidebar_edit_categories.rb

@@ -82,6 +82,24 @@ module PageObjects
         ).click
         self
       end
+
+      def has_tag_in_description?(category)
+        has_css?(
+          ".sidebar-categories-form__category-row[data-category-id='#{category.id}'] .sidebar-categories-form__category-description a.hashtag-cooked[data-type='tag']",
+        )
+      end
+
+      def has_icon_in_description?(category)
+        has_css?(
+          ".sidebar-categories-form__category-row[data-category-id='#{category.id}'] .sidebar-categories-form__category-description a.hashtag-cooked .hashtag-category-icon",
+        )
+      end
+
+      def has_emoji_in_description?(category)
+        has_css?(
+          ".sidebar-categories-form__category-row[data-category-id='#{category.id}'] .sidebar-categories-form__category-description a.hashtag-cooked .hashtag-category-emoji",
+        )
+      end
     end
   end
 end