feat: add Dockerfiles and MySQL TypeORM wiring for center/guild backends

Fabric.Backend.Guild/src/entities/channel.entity.ts

@@ -0,0 +1,20 @@
+import { Column, CreateDateColumn, Entity, Index, PrimaryGeneratedColumn } from 'typeorm';
+
+@Entity('channels')
+export class Channel {
+  @PrimaryGeneratedColumn('uuid')
+  id!: string;
+
+  @Column()
+  guildId!: string;
+
+  @Column()
+  name!: string;
+
+  @Index()
+  @Column({ default: 0 })
+  lastSeq!: number;
+
+  @CreateDateColumn()
+  createdAt!: Date;
+}