Stack the notification timestamp time-over-date instead of a relative string

"1 hour, 20 minutes ago" ran long and ate into the body text's width now
that it's no longer truncated -- a compact two-line HH:MM/date column
(same shape as the calendar row's own day/date marker) fixes that.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ECGMEwrc2k4D8VQuwjstj9

static/css/app.css

@@ -3932,6 +3932,9 @@
   .h-16 {
     height: calc(var(--spacing) * 16);
   }
+  .h-20 {
+    height: calc(var(--spacing) * 20);
+  }
   .h-24 {
     height: calc(var(--spacing) * 24);
   }
@@ -4205,6 +4208,9 @@
   .flex-1 {
     flex: 1;
   }
+  .flex-\[3\] {
+    flex: 3;
+  }
   .flex-shrink {
     flex-shrink: 1;
   }