feat(plan): bulk assignment modal on /plan-work

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

src/admin/hooks/usePlanWork.ts

@@ -488,6 +488,20 @@ export function usePlanWork({ initialDate, canEdit }: UsePlanWorkArgs) {
     },
   });
 
+  const bulkCreate = useMutation({
+    mutationFn: (body: any) =>
+      apiCall("/api/admin/plan/entries/bulk", {
+        method: "POST",
+        body: JSON.stringify(body),
+        headers: { "Content-Type": "application/json" },
+      }),
+    onSuccess: () => {
+      // No optimistic patch — bulk can touch many cells; just invalidate and
+      // let the grid refetch the authoritative state.
+      invalidate();
+    },
+  });
+
   // Roll back an optimistic patch on mutation error. Called from
   // PlanWork's mutation wrappers via `rollbackMutation(mutation, key)`.
   // `mutation` is a TanStack mutation result with a `_rolled` snapshot stashed
@@ -534,6 +548,7 @@ export function usePlanWork({ initialDate, canEdit }: UsePlanWorkArgs) {
     createOverride,
     updateOverride,
     deleteOverride,
+    bulkCreate,
     invalidate,
     // Exposed so PlanWork can roll back an optimistic patch when a
     // mutation throws. Pass the failed mutation and the userId it