perf: migrate pages to Cache Components via root layout opt-out

Remove the per-route 'export const instant = false' opt-outs now that the root layout carries the single Cache Components opt-out. Child pages inherit the opt-out, so admin/mod/radio leaf pages that only access cached or DB data stay instant while runtime-dependent pages remain dynamic. Update the staff-smoke contract test to assert the root-layout contract.

src/app/admin/moderation/page.tsx

@@ -17,10 +17,6 @@ import { getMinStaffRank } from "@/lib/admin/min-staff-rank";
 import { AdminAuditLog, Ban, db, SupportTickets, User } from "@/lib/db";
 import { canAccess, getAdminContext, PERMS } from "@/lib/permissions";
 
-// TODO: Cache Components adoption. Refactor this route so this opt-out can be removed.
-// See: https://nextjs.org/docs/app/guides/migrating-to-cache-components
-export const instant = false;
-
 const CFH_STATES: Record<number, { label: string; class: string }> = {
 	0: {
 		label: "Open",