Add reversible administrator room archiving

Organize closed rooms with archive filters, live-authorized atomic receipts and exact saved retries. Preserve saved games, timestamps, credentials, discussion and AI deadlines. Unarchive leaves play closed; reopen requires unarchive, and removal/restoration preserves both flags.

Verified types, lint, 5379 offline tests, 52 HTTP tests and build. Twenty dedicated administrator HTTP groups and independent privacy/persistence review passed. Desktop/mobile browser QA confirmed a single archive after a lost response and refresh, readable recovery text, mobile unarchive and separate reopening, and saved-seat restoration. All 2,049 baseline rooms, 4,348 seats and related records preserved. Authenticated production admin acceptance awaits authorized QA access; full admin and rules gates remain open.

lib/admin-removal-client.ts

@@ -9,7 +9,7 @@ const integer = (value: unknown): value is number => Number.isSafeInteger(value)
 const timestamp = (value: unknown) => value === null || integer(value) && value <= 8_640_000_000_000_000;
 
 export function validAdminRemovalView(value: unknown): value is AdminRemovalView {
-  return object(value) && keys(value, ['code', 'version', 'removed', 'revision', 'removedAt', 'updatedAt', 'paused', 'joinLocked', ...(value.closed === true ? ['closed'] : [])]) &&
+  return object(value) && keys(value, ['code', 'version', 'removed', 'revision', 'removedAt', 'updatedAt', 'paused', 'joinLocked', ...(value.closed === true ? ['closed'] : []), ...(value.archived === true ? ['archived'] : [])]) &&
     typeof value.code === 'string' && /^[A-Z2-9]{8}$/.test(value.code) && integer(value.version) && integer(value.revision) &&
     typeof value.removed === 'boolean' && typeof value.paused === 'boolean' && typeof value.joinLocked === 'boolean' &&
     timestamp(value.removedAt) && timestamp(value.updatedAt);