fix(calendar): place the event popover again once its note fills it

Popper measures a popover once and watches the window for the rest, and
what a popover holds arrives after it does — the note's editor mounts,
its promoted attributes fill in. A card placed while it was short then
stands where a short card had the room to stand, and its foot falls off
the bottom of the screen.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: eliandoran

apps/client/src/widgets/react/Popover.tsx

@@ -4,9 +4,10 @@ import { createPopper, Instance, Placement, VirtualElement } from "@popperjs/cor
 import clsx from "clsx";
 import { ComponentChildren } from "preact";
 import { createPortal } from "preact/compat";
-import { useEffect, useRef } from "preact/hooks";
+import { useCallback, useEffect, useRef } from "preact/hooks";
 
 import { FLOATING_LAYER_SELECTOR, isWithinFloatingLayer } from "./floating_layers";
+import { useResizeObserver } from "./hooks";
 
 export interface PopoverProps {
     /**
@@ -94,6 +95,10 @@ export default function Popover({ getAnchorRect, placement, updateKey, className
         void popperRef.current?.update();
     }, [ updateKey ]);
 
+    // Placed again whenever what is placed changes size: what a popover holds arrives after it does
+    // — a note's editor mounting, its promoted attributes filling in — and Popper measures it once.
+    useResizeObserver(elRef, useCallback(() => void popperRef.current?.update(), []));
+
     useEffect(() => {
         if (!onDismiss) return;