Add canvas previews, external extension links, and release notes showcase (#1987)

* Add extension thumbnails and preview assets

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Add clickable extension image preview modal

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Address PR review feedback

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Update website/src/styles/global.css

* Add preview assets for canvas extensions

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Update canvas extension preview images

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Delete extensions/backlog-swipe-triage/assets/swipe-canvas-triage.png

* Support external canvas extensions and add Coffilot

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Add homepage link to GitHub repository

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Add release notes showcase canvas extension

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Enhance release notes canvas sourcing and layout

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Aaron Powell <me@aaron-powell.com>

website/src/pages/extensions.astro

@@ -36,6 +36,17 @@ const initialItems = sortExtensions(extensionsData.items, 'title');
           </div>
         </div>
         <div class="resource-list" id="resource-list" role="list" set:html={renderExtensionsHtml(initialItems)}></div>
+        <div id="extension-preview-modal" class="extension-preview-modal hidden" aria-hidden="true">
+          <div class="extension-preview-dialog" role="dialog" aria-modal="true" aria-labelledby="extension-preview-title">
+            <div class="extension-preview-header">
+              <h3 id="extension-preview-title" class="extension-preview-title">Extension preview</h3>
+              <button id="extension-preview-close" class="btn btn-secondary extension-preview-close" type="button" aria-label="Close preview">Close</button>
+            </div>
+            <div class="extension-preview-body">
+              <img id="extension-preview-image" class="extension-preview-image" src="" alt="" />
+            </div>
+          </div>
+        </div>
         <ContributeCTA resourceType="extensions" />
       </div>
     </div>