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/occupancies/dto/occupancy.dto.ts

@@ -0,0 +1,69 @@
+import { IsInt, IsString, IsOptional, IsArray } from 'class-validator';
+
+export class CheckInDto {
+  @IsInt()
+  studentId: number;
+
+  @IsInt()
+  roomId: number;
+
+  @IsString()
+  checkInDate: string; // YYYY-MM-DD
+
+  @IsOptional()
+  @IsString()
+  billingStartDate?: string; // 默认=checkInDate，可调整
+
+  @IsOptional()
+  @IsString()
+  notes?: string;
+}
+
+export class CheckOutDto {
+  @IsString()
+  checkOutDate: string;
+
+  @IsOptional()
+  @IsString()
+  billingEndDate?: string; // 默认=checkOutDate
+
+  @IsOptional()
+  @IsString()
+  checkOutReason?: string;
+}
+
+export class TransferRoomDto {
+  @IsInt()
+  newRoomId: number;
+
+  @IsString()
+  transferDate: string; // YYYY-MM-DD
+
+  @IsOptional()
+  @IsString()
+  oldBillingEndDate?: string; // 旧房计费截止日，默认=transferDate
+
+  @IsOptional()
+  @IsString()
+  newBillingStartDate?: string; // 新房计费起始日，默认=transferDate次日
+
+  @IsOptional()
+  @IsString()
+  reason?: string;
+}
+
+export class BatchCheckOutDto {
+  @IsArray()
+  ids: number[];
+
+  @IsString()
+  checkOutDate: string; // YYYY-MM-DD
+
+  @IsOptional()
+  @IsString()
+  billingEndDate?: string; // 默认=checkOutDate
+
+  @IsOptional()
+  @IsString()
+  checkOutReason?: string;
+}