fix(freight:backoffice): remove coarse fleet.view/fleet.manage/admin fallbacks

Now that every fleet-resource page and settings page has its own
dedicated permission key (previous commit), the broad fallbacks are
redundant and over-grant: anyone holding only fleet:view/fleet:manage
or admin could reach every page in that whole section, not just one.

Removed fleet.view fallback from: Routes, Locomotives, Train Builder,
Wagons, Containers, Cargoes, Compliance & Alerts, Procurement, and the
Overview dashboard's Fleet KPI tab.

Removed fleet.manage fallback from: canFleetAction() (per-resource
fleet CRUD, lib/permissions.ts) and TrainBuilderDetailPage's wagon-
assignment check. Hard-delete already had no such fallback.

Removed admin fallback from: File settings, Dropdown settings,
Contract templates, Portal content, Trade access, Exchange rate.

Left untouched: Incidents (sole gate is fleet.view — no dedicated
edr_freight_app:incidents:* key exists on the backend yet, so there's
nothing to fall back FROM; removing it would make the page
super-admin-only).

Access-narrowing change: anyone currently relying on the coarse grant
without also holding the specific resource/settings key will lose
access to these pages until roles are updated to grant the specific
keys directly. Audit role assignments before this deploys.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/edr-freight-web/backoffice/src/pages/trainBuilder/TrainBuilderDetailPage.tsx

@@ -85,9 +85,7 @@ export default function TrainBuilderDetailPage() {
   const { user } = useAuth();
   const canUpdate = canFleetAction(user, "trains", "update");
   const canDelete = canFleetAction(user, "trains", "delete");
-  const canAssign =
-    hasPermission(user, FREIGHT_PERMS.trains.assignWagons) ||
-    hasPermission(user, FREIGHT_PERMS.fleet.manage);
+  const canAssign = hasPermission(user, FREIGHT_PERMS.trains.assignWagons);
 
   const compositionQuery = useQuery(
     api.trainBuilder.composition.queryOptions({ input: { id }, enabled: Boolean(id) }),