Show save/error status inside the open widget dialog, not behind it

showStatus() always wrote to the page-level #result div, which sits
behind a <dialog>'s backdrop -- a save inside a widget's gear-icon
dialog produced a message the user couldn't see without closing the
dialog first. It now prefers a .dialog-result element inside whichever
<dialog> is currently open, falling back to #result everywhere else.

The dialog is a flex column with its body scrolling independently so
.dialog-result stays pinned as a visible footer regardless of scroll
position -- otherwise a save message on a long form (e.g. the calendar
dialog) could land off-screen below the fold with no visible feedback
at all.

server/app/templates/frame_layout.html

@@ -38,6 +38,7 @@
   <dialog id="widget-dialog">
     <button type="button" id="widget-dialog-close" class="icon-btn" aria-label="Close" title="Close">&times;</button>
     <div id="widget-dialog-body"><p class="sub">Loading...</p></div>
+    <div class="dialog-result"></div>
   </dialog>
 
   <div id="result"></div>