feat(guild): wake_mapping, per-recipient wakeup, discuss/work turn engine, channel join/leave

- wake_mapping table; triage onDuty (auto-added member) / custom listeners
- per-recipient wakeup metadata on message.created (one message-id; added
  only at push). Rules: author=false; triage/custom=wake_mapping only;
  general=all; report=none
- discuss/work rotation: channel_turn_state (order/currentSpeaker/round
  events/cross-round no-reply streak); null activation, queue-jump,
  /no-reply pass, all-/no-reply pause, end-of-round shuffle (trailing
  no-reply run to tail, head shuffled, first != last normal speaker)
- slash-command registry (/no-reply, /force-proceed); registered commands
  intercepted and never delivered; guild-authored /ack persisted
- POST /channels/:id/join|leave; leave cleans channel_members, wake_mapping
  and turn-state order

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

src/channels/turn.module.ts

@@ -0,0 +1,9 @@
+import { Global, Module } from '@nestjs/common';
+import { TurnService } from './turn.service';
+
+@Global()
+@Module({
+  providers: [TurnService],
+  exports: [TurnService],
+})
+export class TurnModule {}