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/TimelineView.tsx

@@ -942,6 +942,7 @@ function TimelineViewContent({
               }}
               anchorX={popover.x}
               anchorY={popover.y}
+              ignoreScrollContainers={[scrollContainerRef]}
             />
           );
         }
@@ -957,6 +958,7 @@ function TimelineViewContent({
             }}
             anchorX={popover.x}
             anchorY={popover.y}
+            ignoreScrollContainers={[scrollContainerRef]}
             {...(popover.contextDate ? { contextDate: popover.contextDate } : {})}
           />
         );
@@ -988,6 +990,7 @@ function TimelineViewContent({
           }}
           anchorX={demandPopover.x}
           anchorY={demandPopover.y}
+          ignoreScrollContainers={[scrollContainerRef]}
         />
       )}
 
@@ -1002,6 +1005,7 @@ function TimelineViewContent({
           anchorY={newAllocPopover.anchorY}
           onClose={() => setNewAllocPopover(null)}
           onCreated={() => setNewAllocPopover(null)}
+          ignoreScrollContainers={[scrollContainerRef]}
         />
       )}