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/runs-query.dto.ts

@@ -0,0 +1,28 @@
+import { ApiPropertyOptional } from "@nestjs/swagger";
+import { Type } from "class-transformer";
+import { IsIn, IsInt, IsOptional, Min } from "class-validator";
+import { RunStatus } from "../scenario-run.entity";
+
+export class RunsQueryDto {
+  @ApiPropertyOptional({ example: 1, default: 1 })
+  @IsOptional()
+  @Type(() => Number)
+  @IsInt()
+  @Min(1)
+  page?: number = 1;
+
+  @ApiPropertyOptional({ example: 20, default: 20 })
+  @IsOptional()
+  @Type(() => Number)
+  @IsInt()
+  @Min(1)
+  limit?: number = 20;
+
+  @ApiPropertyOptional({
+    enum: ["pending", "in_progress", "pass", "fail"],
+    description: "Filter by run status",
+  })
+  @IsOptional()
+  @IsIn(["pending", "in_progress", "pass", "fail"])
+  status?: RunStatus;
+}