fix(timeline): stabilize popovers on internal scroll + expand test coverage

B-1: useViewportPopover — ignoreScrollContainers option; scroll events
originating inside the timeline canvas no longer close point-anchor popovers
B-2: AllocationPopover, DemandPopover, NewAllocationPopover — thread
scrollContainerRef through so horizontal timeline scroll is ignored
B-3: AllocationPopover — staleTime 0 so SSE reconnect triggers immediate refetch
B-4: useViewportPopover.test.ts — 6 new tests (scroll close, ignore container,
resize close, style clamping)
B-5: AllocationPopover.test.tsx — loading state + happy-path tests added

Co-Authored-By: claude-flow <ruv@ruv.net>

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

@@ -1,6 +1,7 @@
 "use client";
 
 import { clsx } from "clsx";
+import type { RefObject } from "react";
 import { useState } from "react";
 import { createPortal } from "react-dom";
 import { AllocationStatus } from "@capakraken/shared";
@@ -20,6 +21,7 @@ interface NewAllocationPopoverProps {
   anchorY: number;
   onClose: () => void;
   onCreated: () => void;
+  ignoreScrollContainers?: RefObject<HTMLElement | null>[];
 }
 
 function toDateInput(d: Date): string {
@@ -38,6 +40,7 @@ export function NewAllocationPopover({
   anchorY,
   onClose,
   onCreated,
+  ignoreScrollContainers,
 }: NewAllocationPopoverProps) {
   const { ref, style } = useViewportPopover({
     anchor: { kind: "point", x: anchorX - 10, y: anchorY },
@@ -45,6 +48,7 @@ export function NewAllocationPopover({
     estimatedHeight: 440,
     onClose,
     ignoreSelectors: ["[data-entity-combobox-overlay='true']"],
+    ...(ignoreScrollContainers ? { ignoreScrollContainers } : {}),
   });
   const invalidateTimeline = useInvalidateTimeline();