feat(task1): restructure directories for turborepo monorepo

- Move backend/ to apps/server/ via git mv
- Move frontend/ to apps/admin/ via git mv
- Create packages/typescript-config/ with base, nestjs, and react-vite presets

apps/server/src/entities/permission.entity.ts

@@ -0,0 +1,19 @@
+import { Entity, PrimaryGeneratedColumn, Column } from 'typeorm';
+
+@Entity('permissions')
+export class Permission {
+  @PrimaryGeneratedColumn()
+  id: number;
+
+  @Column({ type: 'varchar', length: 50, unique: true })
+  code: string;
+
+  @Column({ type: 'varchar', length: 50 })
+  name: string;
+
+  @Column({ type: 'varchar', length: 30 })
+  group: string;
+
+  @Column({ type: 'varchar', length: 200, nullable: true })
+  description: string;
+}