fix(live-preview): navigate popped-out tabs to markdown files

The mdviewr branch in _loadPreview returned before reaching the
StaticServer.redirectAllTabs call that the HTML branch makes, so
popped-out preview windows stopped following along when the user
switched to a markdown file. Broadcast the URL change in the markdown
branch too — popped-out tabs render the legacy server-side markdown
URL while the embedded panel keeps using mdviewr.

Author: abose

src/extensionsIntegrated/Phoenix-live-preview/main.js

@@ -1008,6 +1008,10 @@ define(function (require, exports, module) {
         // Use mdviewr for markdown files (unless custom server is configured)
         if(previewDetails.isMarkdownFile && !previewDetails.isCustomServer && !previewDetails.isNoPreview) {
             _loadMdviewrPreview(previewDetails, force);
+            // Embedded panel uses mdviewr above; popped-out tabs still render
+            // the legacy server-rendered markdown URL, so broadcast the URL
+            // change so they navigate too — same path as the HTML branch.
+            StaticServer.redirectAllTabs(currentLivePreviewURL, force);
             return;
         }
         // Switching away from mdviewr to non-markdown preview