feat(timeline): add pulse animation for in-flight drag mutations

Allocation bars that have active optimistic overrides (post-drag,
awaiting server confirmation) now pulse subtly via animate-pulse.
The pending set is derived from the existing optimisticAllocations
map keys, requiring no additional state.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/api/src/__tests__/timeline-allocation-fragment-support.test.ts

@@ -19,7 +19,7 @@ vi.mock("@capakraken/application", async (importOriginal) => {
     ...actual,
     loadAllocationEntry: loadAllocationEntryMock,
     updateAssignment: updateAssignmentMock,
-    createAssignment: createAssignmentMock,
+    createAssignmentFragment: createAssignmentMock,
     deleteAllocationEntry: deleteAllocationEntryMock,
   };
 });