feat(guild): add 'dm' x-type (private 1:1, always-wake)

channel enum + X_TYPES + realtime XType gain 'dm'. dm channels are
forced private (never public) and non-unique (no dedup; create()
always makes a fresh one). computeWakeup: dm wakes every non-author
participant unconditionally (no rotation / no wake_mapping). The
message.created realtime payload now carries xType so the plugin can
treat dm specially.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/realtime/realtime.gateway.ts

@@ -11,7 +11,7 @@ import { Logger } from '@nestjs/common';
 import { Server, Socket } from 'socket.io';
 import { introspectGuildToken } from '../common/center-auth.js';
 
-type XType = 'general' | 'work' | 'report' | 'discuss' | 'triage' | 'custom';
+type XType = 'general' | 'work' | 'report' | 'discuss' | 'triage' | 'custom' | 'dm';
 
 // Wakeup for non-rotating channels only (general/report/triage/custom).
 // discuss/work go through TurnService + emitMessageTargeted, never here.
@@ -40,6 +40,9 @@ export function computeWakeup(args: {
     case 'triage':
     case 'custom':
       return wakeUserIds.has(recipientUserId);
+    case 'dm':
+      // 1:1 conversation: every non-author participant is always woken.
+      return true;
     default:
       return false;
   }
@@ -189,7 +192,7 @@ export class RealtimeGateway implements OnGatewayConnection, OnGatewayDisconnect
         wakeUserIds: ctx.wakeUserIds,
         mentionUserIds: ctx.mentionUserIds,
       });
-      s.emit('message.created', { ...data, channelId, wakeup });
+      s.emit('message.created', { ...data, channelId, wakeup, xType: ctx.xType });
     }
   }