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/expenses/dto/expense.dto.ts

@@ -0,0 +1,54 @@
+import { IsInt, IsString, IsNumber, IsOptional, IsEnum } from 'class-validator';
+
+export class CreateRoomExpenseDto {
+  @IsInt()
+  roomId: number;
+
+  @IsEnum(['water', 'electricity', 'cleaning', 'damage', 'other'])
+  expenseType: string;
+
+  @IsNumber()
+  amount: number;
+
+  @IsString()
+  periodStart: string;
+
+  @IsString()
+  periodEnd: string;
+
+  @IsOptional()
+  @IsString()
+  description?: string;
+}
+
+export class CreatePersonalExpenseDto {
+  @IsInt()
+  studentId: number;
+
+  @IsOptional()
+  @IsInt()
+  roomId?: number;
+
+  @IsEnum(['damage', 'cleaning', 'penalty', 'key', 'remote', 'deposit_deduction', 'other'])
+  expenseType: string;
+
+  @IsNumber()
+  amount: number;
+
+  @IsString()
+  expenseDate: string;
+
+  @IsOptional()
+  @IsString()
+  description?: string;
+}
+
+export class BatchRoomExpenseDto {
+  @IsString()
+  periodStart: string;
+
+  @IsString()
+  periodEnd: string;
+
+  expenses: { roomId: number; expenseType: string; amount: number; description?: string }[];
+}