fix(web): portal timeline overlays above stacked panels

apps/web/src/components/timeline/DemandPopover.tsx

@@ -1,5 +1,6 @@
 "use client";
 
+import { createPortal } from "react-dom";
 import type { TimelineDemandEntry } from "./TimelineContext.js";
 import { formatCents, formatDateLong } from "~/lib/format.js";
 import { useViewportPopover } from "~/hooks/useViewportPopover.js";
@@ -36,7 +37,7 @@ export function DemandPopover({
   const totalHours = demand.hoursPerDay * days;
   const budgetCents = demand.dailyCostCents * days;
 
-  return (
+  const popover = (
     <div
       ref={ref}
       style={style}
@@ -171,4 +172,6 @@ export function DemandPopover({
       </div>
     </div>
   );
+
+  return typeof document === "undefined" ? popover : createPortal(popover, document.body);
 }