feat(web): IA-3 navigation, legacy redirects and top-bar inbox (FE-1)

Sidebar becomes 5 groups (overview / resources / subscriptions / organize /
system). Pending items move to a top-bar inbox with badge and grouped
dropdown. Engine panel, schedules and identity pages redirect to the task
page, its plan tab and media overview views; the download plan becomes a
second tab of the download panel. nav.test and smoke cover the new routes.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

apps/web/app/api/decisions.ts

@@ -25,8 +25,9 @@ export { DecisionSummary };
 
 const Page = cursorPage(Decision);
 
-export function useDecisions(filters: DecisionFilters) {
+export function useDecisions(filters: DecisionFilters, enabled = true) {
   return useInfiniteQuery({
+    enabled,
     queryKey: decisionKeys.list(filters),
     initialPageParam: undefined as string | undefined,
     queryFn: ({ pageParam, signal }) =>