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/AllocationPopover.test.tsx

@@ -42,6 +42,14 @@ vi.mock("~/hooks/useViewportPopover.js", () => ({
   }),
 }));
 
+vi.mock("~/components/ui/DateInput.js", () => ({
+  DateInput: () => null,
+}));
+
+vi.mock("~/components/ui/ProjectCombobox.js", () => ({
+  ProjectCombobox: () => null,
+}));
+
 describe("AllocationPopover", () => {
   beforeEach(() => {
     mockUseQuery.mockReset();
@@ -93,4 +101,67 @@ describe("AllocationPopover", () => {
     expect(html).toContain("data-testid=\"timeline-allocation-popover-unavailable\"");
     expect(html).toContain("The selected booking could not be resolved from the current timeline data.");
   });
+
+  it("renders a loading skeleton when the allocation is being fetched", () => {
+    mockUseQuery.mockReturnValue({
+      data: undefined,
+      isLoading: true,
+      error: null,
+    });
+
+    const html = renderToStaticMarkup(
+      <AllocationPopover
+        allocationId="assignment_loading"
+        projectId="project_1"
+        anchorX={120}
+        anchorY={40}
+        onClose={() => {}}
+        onOpenPanel={() => {}}
+      />,
+    );
+
+    expect(html).toContain("data-testid=\"timeline-allocation-popover-loading\"");
+  });
+
+  it("renders allocation data when provided as initialAllocation", () => {
+    // useQuery is always called (with enabled: false), so we need a baseline return value
+    mockUseQuery.mockReturnValue({
+      data: undefined,
+      isLoading: false,
+      error: null,
+    });
+
+    const allocation = {
+      id: "assignment_1",
+      entityId: "assignment_1",
+      projectId: "project_1",
+      resourceId: "resource_1",
+      startDate: new Date("2026-01-01"),
+      endDate: new Date("2026-01-31"),
+      hoursPerDay: 8,
+      role: "Developer",
+      metadata: null,
+      resource: {
+        displayName: "Alice Smith",
+        eid: "alice.smith",
+        lcrCents: 0,
+      },
+    };
+
+    const html = renderToStaticMarkup(
+      <AllocationPopover
+        allocationId="assignment_1"
+        projectId="project_1"
+        initialAllocation={allocation as any}
+        anchorX={120}
+        anchorY={40}
+        onClose={() => {}}
+        onOpenPanel={() => {}}
+      />,
+    );
+
+    expect(html).not.toContain("data-testid=\"timeline-allocation-popover-error\"");
+    expect(html).not.toContain("data-testid=\"timeline-allocation-popover-unavailable\"");
+    expect(html).not.toContain("data-testid=\"timeline-allocation-popover-loading\"");
+  });
 });