Add administrative room close and reopen controls

Preserve readable private tables, discussion and pending games while closure blocks new play, joins, messages, AI and seat mutations. Add live-authorized atomic closure audits, room-version/revision fences, dedicated controls and exact saved retries. Reopen with the saved pause/join settings and current credentials; restoring a removed but closed room keeps its AI stopped.

Verified types, lint, 5356 offline tests, 52 HTTP tests and build. Seventeen dedicated authenticated HTTP groups and independent privacy/persistence review passed. Desktop/mobile browser QA confirmed one close after a lost response and refresh, persistent readable notices, retained private draft, mobile reopening and saved-seat refresh. All 2,001 baseline rooms, 4,243 seats and related records preserved. Positive production admin acceptance awaits authorized QA access; full admin and rules gates remain open.

components/room-control-notice.tsx

@@ -2,6 +2,11 @@ import type { RoomControl } from '@/lib/room-control';
 
 /** Public operational status only; administrator reasons and identity stay private. */
 export function RoomControlNotice({ control }: { control?: RoomControl }) {
+  if (control?.closed) return <section className="notice" aria-label="Room availability" aria-live="polite">
+    <h2 className="text-lg font-semibold">Room closed by an administrator</h2>
+    <p>This room is closed to further play. Your table and discussion history remain readable. The saved position and pending choices are preserved; closing does not award a winner.</p>
+    <p>New joins, game decisions, AI, messages and seat changes are stopped. Keep any unconfirmed request and recovery kit. Exact saved requests can still confirm an earlier completed action. An administrator can reopen the room.</p>
+  </section>;
   if (!control?.paused && !control?.joinLocked) return null;
   return <section className="notice" aria-label="Room availability" aria-live="polite">
     {control.paused ? <>