chore(repo): restructure as monorepo with server and client workspaces

- move NestJS app into server/ subdirectory
- add client/ React+TypeScript (Vite) app with Hello World
- update docker-compose to build and run both services
- add root package.json declaring npm workspaces
- update .gitignore to cover node_modules and dist at all depths

server/src/scenario/dto/create-scenario.dto.ts

@@ -0,0 +1,9 @@
+import { ApiProperty } from "@nestjs/swagger";
+import { IsNotEmpty, IsString } from "class-validator";
+
+export class CreateScenarioDto {
+  @ApiProperty({ example: "Login and verify cabinet" })
+  @IsString()
+  @IsNotEmpty()
+  name: string;
+}