Make plan deletion visible and reliable with in-page confirmation

public/app.css

@@ -4422,3 +4422,9 @@ select.f {
 .planner-page .header-row-top {
 	max-width: 100%;
 }
+
+.delete-plan-dialog { width: min(500px, 94vw); }
+#delete-plan-name { font-weight: 700; overflow-wrap: anywhere; }
+#delete-plan-description { line-height: 1.6; }
+#delete-plan-error { color: #a32920; }
+.delete-plan-actions { display: flex; justify-content: flex-end; gap: 12px; margin-top: 24px; }