fix(vim): redraw after :NuwikiExportBrowse shells out to the browser

A silent `:!xdg-open`/`:!open` swaps to the shell's alternate screen and
returns without repainting, leaving the editor UI garbled until the next
redraw. Force a full repaint after launching the browser. Neovim already
avoids this via async jobstart.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

autoload/nuwiki/commands.vim

@@ -598,7 +598,12 @@ function! s:open_browser(notification) abort
     silent execute '!xdg-open ' . shellescape(l:url, 1) . ' &'
   else
     echom 'nuwiki: exported → ' . l:url
+    return
   endif
+  " A silent `:!` shells out via the alternate screen and returns without
+  " repainting, leaving the editor UI garbled until the next redraw. Force a
+  " full repaint so the browser launch doesn't leave visual artifacts behind.
+  redraw!
 endfunction
 
 " ===== File ops =====