feedback3: merge W3E — two spectator seats per co-op room (GitHub-relayed community request #26; a remake feature): watch like an eliminated player, never act, no private data

shared/protocol.js

@@ -251,6 +251,11 @@ export const C2S = {
   'room.start': {},
   // operator loadout (DESIGN §16): stored per session/seat; accepted until the match leaves INFO_CHECK
   'room.loadout': { entries: isLoadoutEntries },
+  // spectator seats (remake feature, community report #26; MAX_SPECTATORS): take one of a co-op room's spectator seats —
+  // in its lobby or while its match runs — never a player seat; the host frees one by playerId (the spectator gets
+  // room.closed { reason: 'kicked' }). room.leave / g.leave leave a spectator seat like a player seat.
+  'room.spectate': { code: (v) => isStr(v, ROOM_CODE_LEN + 2) && /^[A-Za-z0-9]+$/.test(v) },
+  'room.removeSpectator': { playerId: isId },
 
   // match
   'g.infoReady': {},