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/router/assistant-tools.ts

@@ -9,6 +9,7 @@ import {
   AllocationStatus,
   PermissionKey,
   SystemRole,
+  toIsoDateOrNull,
 } from "@capakraken/shared";
 import type { WeekdayAvailability } from "@capakraken/shared";
 import { TRPCError } from "@trpc/server";
@@ -269,9 +270,7 @@ const createStaffingCaller = createCallerFactory(staffingRouter);
 
 // ─── Helpers ────────────────────────────────────────────────────────────────
 
-function fmtDate(d: Date | null | undefined): string | null {
-  return d ? d.toISOString().slice(0, 10) : null;
-}
+const fmtDate = toIsoDateOrNull;
 
 class AssistantVisibleError extends Error {
   constructor(message: string) {
@@ -301,7 +300,7 @@ function formatHolidayCalendarEntry(entry: {
 }) {
   return {
     id: entry.id,
-    date: fmtDate(entry.date),
+    date: toIsoDateOrNull(entry.date),
     name: entry.name,
     isRecurringAnnual: entry.isRecurringAnnual ?? false,
     source: entry.source ?? null,