feat(fleet): move bulk Remote OTA updates to Community tier (#1151)

Drops `requirePaid` from `POST /api/fleet/update-all` so Community admins
can dispatch bulk node updates. Per-node OTA was already Community-
reachable (admin-only); this completes the move so the full Remote OTA
surface ships at Community.

Frontend mirrors the backend: removes `canBulkUpdate` from
NodeUpdatesSheet so the "Update all (N)" affordance is purely data-
driven on `updatableRemoteCount > 0`.

Docs realigned to drop fence-spec and Skipper-only phrasing on the
Update all bulk action:
- features/licensing.mdx: Community line now lists Remote OTA (per-node
  and Update all); Skipper Fleet Actions parenthetical drops "bulk
  update all"
- features/remote-updates.mdx: Note rewritten to role-only requirement
- features/fleet-view.mdx: Update all (n) bullet drops the tier clause
- features/overview.mdx: Fleet View and Remote updates blurbs drop the
  Skipper/Admiral fences
- operations/upgrade.mdx: Note rephrased without naming tiers

Test coverage:
- fleet.test.ts: tier-gating spec flipped to assert Community access
- fleet-pilot-update.test.ts: bulk-OTA dispatch suite now spies tier
  to Community so it doubles as a regression guard

frontend/src/components/FleetView.tsx

@@ -242,7 +242,6 @@ export function FleetView({ onNavigateToNode }: FleetViewProps) {
                 retryNodeUpdate={updateStatus.retryNodeUpdate}
                 dismissNodeUpdate={updateStatus.dismissNodeUpdate}
                 triggerUpdateAll={updateStatus.triggerUpdateAll}
-                canBulkUpdate={isPaid}
             />
 
             <LocalUpdateConfirmDialog