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.

README.md

@@ -48,7 +48,9 @@ an explicitly owned new host seat and initial AI players.
 [Configure lobby](docs/ADMIN_LOBBY_CONFIGURATION.md) manages supported rules, AI
 seats and host assignment without private seat access.
 [Remove or restore](docs/ADMIN_ROOM_REMOVAL.md) recoverably removes selected rooms;
-use the Directory filter to find them for restoration. Close/end, archive,
+use the Directory filter to find them for restoration.
+[Close or reopen](docs/ADMIN_ROOM_CLOSURE.md) stops further play while preserving
+readable tables and history, then resumes the same saved position. Archive,
 permanent deletion, participant support and backup tools are still being built.
 
 ## Saved seats and reconnecting