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/static/theme.css

@@ -402,6 +402,13 @@ button.secondary:hover { background: var(--surface-alt); }
   background: var(--surface);
   color: var(--text);
   box-shadow: var(--shadow-hover);
+  /* #widget-dialog-body scrolls on its own (min-height: 0 is what lets a
+     flex child actually shrink/scroll instead of forcing the dialog
+     past max-height) so .dialog-result stays pinned as a visible footer
+     regardless of scroll position -- otherwise a save message can land
+     off-screen below a long form with no visible feedback at all. */
+  display: flex;
+  flex-direction: column;
 }
 #widget-dialog::backdrop { background: var(--overlay); }
 #widget-dialog-close {
@@ -414,8 +421,11 @@ button.secondary:hover { background: var(--surface-alt); }
   z-index: 1;
 }
 .dialog-title { margin: 0 40px 16px 0; font-size: 18px; }
+#widget-dialog-body { overflow-y: auto; min-height: 0; }
 #widget-dialog-body .card { box-shadow: none; }
 #widget-dialog-body .card:first-child { margin-top: 0; }
+.dialog-result { flex: none; }
+.dialog-result:not(:empty) { margin-top: 16px; padding-top: 16px; border-top: 1px solid var(--border); }
 
 code {
   background: var(--surface-alt);