feat(guild): validate bearer tokens via center introspection

src/channels/channels.service.ts

@@ -18,6 +18,13 @@ export class ChannelsService {
     });
   }
 
+  listAll() {
+    return this.channelRepo.find({
+      order: { createdAt: 'ASC' },
+      take: 200,
+    });
+  }
+
   create(input: Partial<Channel>) {
     const channel = this.channelRepo.create({
       guildId: String(input.guildId ?? ''),